Local contraction of flexible bodies using balloon expansion for extension-contraction catheter articulation and other uses

ABSTRACT

Articulation devices, systems, and methods for articulating elongate flexible structures can locally contract a flexible elongate frame or skeleton of an elongate flexible body such as a catheter. Balloons along one side of an axial segment of the elongate flexible body can be inflated so as to help define a resting shape of the elongate body. The skeleton may have pairs of corresponding axially oriented surface regions coupled to each other by a loop of a deformable helical coil structure. Balloons may be between the regions, and the pairs may be separated by an offset that increases when the axis of the skeleton is axially compressed. Inflation of the balloons can axially contract or shorten the skeleton adjacent the balloons so that the elongate body bends toward the balloons. Different sets of balloons may apply opposing local axial elongation and contraction forces so that selective inflation and deflation of subsets of the balloons can controllably bend and/or change an overall axial length of the elongate body throughout a workspace. Varying the inflation pressures of the opposed balloons can controllably and locally modulate the stiffness of the elongate body.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of priority from co-assignedU.S. Provisional Patent App. Nos. 62/296,409, filed on Feb. 17, 2016,entitled “LOCAL CONTRACTION OF FLEXIBLE BODIES USING BALLOON EXPANSIONFOR EXTENSION-CONTRACTION CATHETER ARTICULATION AND OTHER USES”(Attorney Docket No. 097805-000300US-0970626); and 62/401,005 filed onSep. 28, 2016, entitled “BASE STATION CHARGER AND SERVER FOR HANDHELDROBOTIC CATHETER SYSTEMS AND OTHER USES, AND IMPROVED ARTICULATEDDEVICES AND SYSTEMS” (Attorney Docket No. 097805-000900US-1014595), thefull disclosures of which are incorporated herein for all purposes.

The subject matter of the present application is related to that ofco-assigned U.S. patent application Ser. No. 15/081,026 filed on Mar.25, 2016, entitled “Articulation Systems, Devices, and Methods forCatheters and Other Uses ” (US Patent Publication No. US20160279388,Attorney Docket No. 097805-000130US-0970623); and to that of co-assignedU.S. patent application Ser. No. 15/369,606, filed on Dec. 5, 2016,entitled “Input and Articulation System for Catheters and Other Uses”(Attorney Docket No. 097805-000220US-1015830), the full disclosures ofwhich are incorporated herein for all purposes.

FIELD OF THE INVENTION

In general, the present invention provides articulation devices,systems, and methods for elongate flexible structures. In exemplaryembodiments, the invention provides systems having a fluid-drivenballoon array that can be used to controllable and locally axiallycontract a frame or skeleton (for example, along one or more selectedside(s) of one or more selected axial segment(s)) of an elongateflexible body so as to help define a resting shape or pose of theelongate body. In preferred embodiments, the invention provides improvedmedical devices, systems, and methods, including improved articulationdevices, systems, and methods for selectively bending of, altering thebend characteristics of, and/or altering the lengths of elongateflexible medical structures such as catheters, guidewires, and the like.

BACKGROUND OF THE INVENTION

Diagnosing and treating disease often involve accessing internal tissuesof the human body. Once the tissues have been accessed, medicaltechnology offers a wide range of diagnostic tools to evaluate tissuesand identify lesions or disease states. Similarly, a number oftherapeutic tools have been developed that can help surgeons interactwith, remodel, deliver drugs to, or remove tissues associated with adisease state so as to improve the health and quality of life of thepatient. Unfortunately, gaining access to and aligning tools with theappropriate internal tissues for evaluation or treatment can represent asignificant challenge to the physician, can cause serious pain to thepatient, and may (at least in the near term) be seriously detrimental tothe patient's health.

Open surgery is often the most straightforward approach for gainingaccess to internal tissues. Open surgery can provide such access byincising and displacing overlying tissues so as to allow the surgeon tomanually interact with the target internal tissue structures of thebody. This standard approach often makes use of simple, hand-held toolssuch as scalpels, clamps, sutures, and the like. Open surgery remains,for many conditions, a preferred approach. Although open surgicaltechniques have been highly successful, they can impose significanttrauma to collateral tissues, with much of that trauma being associatedwith gaining access to the tissues to be treated.

To help avoid the trauma associated with open surgery, a number ofminimally invasive surgical access and treatment technologies have beendeveloped. Many minimally invasive techniques involve accessing thevasculature, often through the skin of the thigh, neck, or arm. One ormore elongate flexible catheter structures can then be advanced alongthe network of blood vessel lumens extending throughout the body and itsorgans. While generally limiting trauma to the patient, catheter-basedendoluminal therapies are often reliant on specialized cathetermanipulation techniques to safely and accurately gain access to a targetregion, to position a particular catheter-based tool in alignment with aparticular target tissue, and/or to activate or use the tool. In fact,some endoluminal techniques that are relatively simple in concept can bevery challenging (or even impossible) in practice (depending on theanatomy of a particular patient and the skill of a particularphysician). More specifically, advancing a flexible guidewire and/orcatheter through a tortuously branched network of body lumens might becompared to pushing a rope. As the flexible elongate body advancesaround first one curve and then another, and through a series of branchintersections, the catheter/tissue frictional forces, resilient energystorage (by the tissue and the elongate body), and other movementinteractions may become more complex and unpredictable, and control overthe rotational and axial position of the distal end of a catheter canbecome more challenging and less precise. Hence, accurately aligningthese elongate flexible devices with the desired luminal pathway andtarget tissues can be a significant challenge.

A variety of mechanisms can be employed to steer or variably alterdeflection of a tip of a guidewire or catheter in one or more lateraldirections to facilitate endoluminal and other minimally invasivetechniques. Pull wires may be the most common catheter tip deflectionstructures and work well for many catheter systems by, for example,controllably decreasing separation between loops along one side of ahelical coil, braid, or cut hypotube near the end of a catheter or wire.Complex and specialized catheter systems having dozens of pull wireshave been proposed and built, in some cases with each pull wire beingarticulated by a dedicated motor. Alternative articulation systems havealso been proposed: work in connection with the present invention haspresented a particularly advantageous system which includes an array ofsmall balloons that can be inflated to alter the separation betweenloops of a coil or the like. Still further alternative systems have beenproposed that include electrically actuated shape memory alloystructures, piezoelectric actuation, phase change actuation, and thelike. As the capabilities of steerable systems increase, the range oftherapies being implemented using these technologies should continue toexpand.

Unfortunately, as articulation systems for catheters get more complex,it can be more and more challenging to maintain accurate control overthese flexible bodies. For example, pull wires that pass through bentflexible catheters often slide over surfaces within the catheter, withthe sliding interaction extending around bends. Hysteresis and frictionof a pull-wire system may vary significantly with different overallconfigurations of the bends, so that the articulation system responsemay be difficult to predict and control. Hence, there could be benefitsto providing more accurate small and precise motions, to improve the lagtime, and/or to provide improved transmission of motion over knowncatheter pull-wire systems to enhance coordination between the input andoutput of catheters and other elongate flexible tools.

Along with catheter-based therapies, a number of additional minimallyinvasive surgical technologies have been developed to help treatinternal tissues while avoiding at least some of the trauma associatedwith open surgery. Among the most impressive of these technologies isrobotic surgery. Robotic surgeries often involve inserting one end of anelongate rigid shaft into a patient, and moving the other end with acomputer-controlled robotic linkage so that the shaft pivots about aminimally invasive aperture. Surgical tools can be mounted on the distalends of the shafts so that they move within the body, and the surgeoncan remotely position and manipulate these tools by moving input deviceswith reference to an image captured by a camera from within the sameworkspace, thereby allowing precisely scaled micro-surgery. Alternativerobotic systems have also been proposed for manipulation of the proximalend of flexible catheter bodies from outside the patient so as toposition distal treatment tools. These attempts to provide automatedcatheter control have met with challenges, which may be in-part becauseof the difficulties in providing accurate control at the distal end of aflexible elongate body using pull-wires extending along bending bodylumens. Still further alternative catheter control systems apply largemagnetic fields using coils outside the patient's body to directcatheters inside the heart of the patient, and more recent proposalsseek to combine magnetic and robotic catheter control techniques. Whilethe potential improvements to control surgical accuracy make all ofthese efforts alluring, the capital equipment costs and overall burdento the healthcare system of these large, specialized systems is aconcern, and precise robotic control of some or all of these system canstill be a challenge.

In light of the above, it would be beneficial to provide new andimproved articulation devices, system, and methods for use with elongateflexible structures. It would also be beneficial to provide improvedmedical devices, systems, and methods, particularly those that involvethe use of elongate flexible bodies such as catheters, guidewires, andother flexible minimally invasive surgical tools. It would be desirableif these improved technologies could offer improved controllability overthe resting or nominal shape of a skeleton of a flexible body, and stillallow the overall body to bend (safely and predictably) against softtissues, ideally without requiring the use of very expensive components,large numbers of parts, and/or exotic materials.

BRIEF SUMMARY OF THE INVENTION

The present invention generally provides articulation devices, systems,and methods for articulating elongate flexible structures. Exemplaryembodiments provide systems having a fluid-driven balloon array that canbe used to locally contract a flexible elongate frame or skeleton (forexample, along one or more selected side(s) of one or more selectedaxial segment(s)) of an elongate flexible body so as to help define aresting shape or pose of the elongate body. In preferred embodiments,the invention provides improved medical devices, systems, and methods,including improved articulation devices, systems, and methods forselectively bending of, altering the bend characteristics of, and/oraltering the lengths of elongate flexible medical structures such ascatheters, guidewires, and the like. The skeleton structures describedherein will often have pairs of corresponding axially oriented surfaceregions that can move relative to each other, for example, with theregions being on either side of a sliding joint, or coupled to eachother by a loop of a deformable helical coil structure of the skeleton.A balloon of the array (or some other actuator) may be between theregions of the pairs. One or more of these pairs of surfaces may beseparated by an offset that increases when the axis of the skeleton iscompressed near the pair. While it may be counterintuitive, axialexpansion of the balloon (or another actuator) between such regions canaxially contract or shorten the skeleton near the balloon, for example,bending the skeleton toward a balloon that is offset laterally from theaxis of the elongate body. Advantageously, the skeleton and balloonarray can be configured so that different balloons apply opposing localaxial elongation and contraction forces. Hence, selective inflation ofsubsets of the balloons and corresponding deflation of other subsets ofthe balloons can be used to controllably urge an elongate flexible bodyto bend laterally in a desired direction, to change in overall axiallength, and/or to do a controlled combination of both throughout aworkspace. Furthermore, varying the inflation pressures of the opposedballoons can controllably and locally modulate the stiffness of theelongate body, optionally without changing the pose of the articulatedelongate body.

In a first aspect, the invention provides an articulable cathetercomprising at least one elongate skeleton having a proximal end and adistal end and defining an axis therebetween. The skeleton includes aninner wall and an outer wall with a first flange affixed to the innerwall and a second flange affixed to the outer wall. Opposed majorsurfaces of the walls may be oriented primarily radially, and opposedmajor surfaces of the flanges may be oriented primarily axially. Aplurality of axial contraction balloons can be disposed radially betweenthe inner wall and the outer wall, and axially between the first flangeand the second flange so that, in use, inflation of the contractionballoons pushes the first and second flanges axially apart so as to urgean axial overlap of the inner and outer walls to increase. This canresult in the skeleton adjacent the inflated contraction balloons beinglocally urged to axially contract in response to the inflating of theballoon.

In some embodiments, the skeleton comprises a plurality of annular orring structures, often including a plurality of inner rings having theinner walls and a plurality of outer rings having the outer walls. Theflanges of such embodiments may comprise annular flanges affixed to thewalls, and the annular structures or rings may be axially movablerelative to each other. Typically, each ring will include an associatedwall and will have a proximal ring end and a distal ring end, with thewall of the ring affixed to an associated proximal flange at theproximal ring end and to an associated distal flange at the distal ringend, the first and second flanges being included among the proximal anddistal flanges.

In other embodiments, the skeleton comprises at least one helicalmember. For example, the walls may comprise helical walls, and theflanges may comprise helical flanges affixed to the helical walls, thehelical member(s) including the walls and the flanges. The helicalmember may define a plurality of helical loops and the loops may beaxially movable relative to each other sufficiently to accommodatearticulation of the skeleton. Preferably, each loop has an associatedwall with a proximal loop edge and a distal loop edge, the wall beingaffixed to an associated proximal flange at the proximal loop edge andto an associated distal flange at the distal loop edge (the first andsecond flanges typically being included among these proximal and distalflanges).

In the ring embodiments, the helical embodiments, and other embodiments,a plurality of axial extension balloons may be disposed axially betweenadjacent flanges of the skeleton. Typically, only one of the walls ofthe skeleton (for example, an inner wall or an outer wall but not both)may be disposed radially of the extension balloons themselves. In otherwords, unlike many of the contraction balloons, the extension balloonsare preferably not contained radially in a space between an inner walland an outer wall. As a result, and unlike the contraction balloons,inflation of the the extension balloons during use will push theadjacent flanges axially apart so as to urge the skeleton adjacent theinflated extension balloons to locally elongate axially.

In particularly advantageous embodiments, the extension balloons and thecontraction balloons can be mounted to the skeleton in opposition sothat inflation of the extension balloons and deflation of thecontraction balloons locally axially elongates the skeleton, and so thatdeflation of the extension balloons and inflation of the contractionballoons locally axially contracts the skeleton. Note that the balloonscan be distributed circumferentially about the axis so that selectiveinflation of a first eccentric subset of the balloons and selectivedeflation of a second eccentric subset of the balloons can laterallydeflect the axis toward a first lateral orientation, and so thatselective deflation of the first eccentric subset of the balloons andselective inflation of the second eccentric subset of the balloons canlaterally deflect the axis away from the first lateral orientation. Theballoons can also (or instead) be distributed axially along the axis sothat selective inflation of a third eccentric subset of the balloons andselective deflation of a fourth eccentric subset of the balloons maylaterally deflect the axis along a first axial segment of the skeleton,and selective deflation of a fifth eccentric subset of the balloons andselective inflation of a sixth eccentric subset of the balloonslaterally deflects the axis along a second axial segment of theskeleton, the second axial segment being axially offset from the firstaxial segment.

Most embodiments of the systems and devices described herein, andparticularly those embodiments having skeletons formed using helicalstructural members, may benefit from groups of the balloons having outersurfaces defined by a shared flexible tube. The tube may have across-section that varies periodically along the axis, and a multi-lumenshaft can be disposed within the flexible tube. The tube may be sealedto the shaft intermittently along the axis, with radial ports extendingbetween interiors of the balloons and a plurality of lumens of themulti-lumen shaft so as to facilitate inflation of selectable subsets ofthe balloons by directing inflation fluid along a subset of the lumens.In exemplary embodiments, the inflation fluid may comprise gas withinthe balloons and liquid within the inflation lumens.

In another aspect, the invention provides an articulable flexible systemcomprising an elongate flexible structural skeleton having a proximalend and a distal end with an axis extending therebetween. The skeletonincludes a plurality of eccentric pairs of surface regions that eachdefine an associated offset between the surface regions of that pair. Aplurality of extension actuators are included, with each extensionactuator coupling the surface regions of an associated pair so thatenergizing of the extension actuator urges local axial elongation of theskeleton. A plurality of contraction actuators may also be provided,with each contraction actuator coupling the surface regions of anassociated pair so that energizing of the contraction actuator urgeslocal axial contraction of the skeleton. The contraction actuators canbe mounted to the skeleton substantially in opposition to the extensionactuators, and an energy supply system can be coupled with the actuatorsso as to simultaneously energize both the extension actuators and thecontraction actuators during use such that an axial stiffness of thearticulable flexible structure can be modulated.

Optionally, the system allows the stiffness to be controllably andselectably increased from a nominal non-energized actuator stiffness toan intermediate stiffness configuration (with the actuators partiallyenergized, and/or to a relatively high stiffness configuration (with theactuators more fully or fully energized). Different axial segments maybe controllably varied (so that a first segment has any of a pluralityof different stiffnesses, and a second segment independently has any ofa plurality of different stiffnesses). In exemplary embodiments, theenergy supply system may comprise a pressurized fluid source and theenergizing of the actuators may comprise pressurizing the actuators (theactuators often comprising fluid-expandable bodies such as balloons orthe like).

In another aspect, the invention provides an articulable flexible devicecomprising an elongate structural skeleton having a proximal end and adistal end with an axis therebetween. The structural skeleton hereincludes a helical channel with a proximal channel boundary and a distalchannel boundary. A helical member is axially movable within the helicalchannel in correlation with local axial elongation and contraction ofthe skeleton (which can facilitate using the helical member to vary theshape of the skeleton, for example, by pushing helical member axiallytoward the proximal or distal boundary). A first helical actuationassembly may be disposed within the channel, the first helical actuationassembly comprising a first helical fluid conduit with a first pluralityof fluid supply channels. The first helical actuation assembly may alsoinclude a first plurality of fluid-expandable bodies in fluidcommunication with the first channels, and these may be mounted withinthe channel so as to span between the proximal channel boundary and thehelical member (at least when inflated). A second helical actuationassembly may also be disposed within the channel, the second helicalactuation assembly comprising a second helical fluid conduit with asecond plurality of fluid supply channels, along with a second pluralityof fluid-expandable bodies in fluid communication with the secondchannels. These second fluid expandable bodies may be positioned in thechannel so as to span between the distal channel boundary and thehelical member (at least when inflated) such that axial positioning ofthe helical member within the channel is constrained by inflation statesof the the first and second plurality of fluid-expandable bodies. Theability to constrain the position of the helical member within thechannel with just the two balloon arrays (or arrays of other expandablebodies, and rather than having to coordinate inflation and deflation ofballoons from a larger number of separate balloon arrays, such as fromthree, four, five, or even six inflation assemblies) can significantlyreduce the complexity and improve the performance of the articulationsystem.

In yet another aspect, the invention provides an articulable flexibledevice comprising an elongate structural skeleton having a proximal endand a distal end with an axis therebetween. The structural skeleton hasa helical member and first and second axial segments between theproximal and distal ends. A helical fluid conduit extends axially alongthe skeleton, the conduit having a first plurality of fluid supplychannels and a second plurality of fluid supply channels. A firstplurality of fluid-expandable bodies is disposed along the first segmentand is coupled with the first fluid supply channels so as to facilitatearticulation of the first segment with a first plurality of degrees offreedom. A second plurality of fluid-expandable bodies is disposed alongthe second segment and is coupled with the second fluid supply channelsso as to facilitate articulation of the second segment with a secondplurality of degrees of freedom. Advantageously, rather than having torely entirely on different conduits for different axial segments (thatprovide, for example, independent degrees of freedom), this aspect ofthe invention allows a common and/or continuous helical conduit to beused for two, three, four, or more segments, typically with each segmentaccommodating multiple degrees of freedom.

In yet another aspect, the invention provides an articulable flexibledevice comprising an elongate structural skeleton having a proximal endand a distal end with an axis therebetween. The structural skeleton hasa helical member and an axial segment between the proximal and distalends. A helical fluid conduit extends axially along the skeleton, theconduit having a plurality of fluid channels. A plurality offluid-expandable bodies are distributed axially and circumferentiallyalong the segment and are coupled to the fluid channels so thatinflation of the balloons during use bends the skeleton along thesegment in first and second transverse lateral bending axes, and alsoaxially elongates the skeleton along the segment so that the segment ofthe skeleton articulates with three degrees of freedom.

In exemplary embodiments, a first subset of the fluid-expandable bodiesis disposed substantially axisymmetrical along the segment of theskeleton such that inflation of the first subset axially elongates thesegment. A second subset of the fluid-expandable bodies may bedistributed eccentrically along the segment such that inflation of thesecond subset laterally bends the segment along the first lateralbending axis. A third subset of the fluid-expandable bodies may bedistributed eccentrically along the segment such that inflation of thethird subset laterally bends the segment along the second lateralbending axis and transverse to the first bending axis. The second andthird subsets will often axially overlap the first subset. Optionally, afourth subset of the fluid-expandable bodies may be supported by theskeleton substantially in opposition to the first subset and a fifthsubset of the fluid-expandable bodies can similarly be substantially inopposition to the second subset, with a sixth subset of the fluidexpandable bodies substantially in opposition to the third subset. Thiscan facilitate using selective inflation of the subsets to controllablyand reversibly articulate the segment throughout a three-dimensionalworkspace.

In a still further aspect, the invention provides an articulablestructure comprising an elongate flexible structural skeleton having aproximal end and a distal end with an axis extending therebetween. Theskeleton comprises at least one helical member having a contractionoffset defined between an associated proximally oriented surface and anassociated distally oriented surface. The contraction offset decreaseswith local axial elongation and increases with local axial contractionof the skeleton. A balloon is disposed in the contraction offset suchthat inflation of the balloon increases the offset and urges axialcontraction of the skeleton.

In a still further aspect, the invention provides an articulablestructure comprising an elongate flexible structural skeleton having aproximal end and a distal end with an axis therebetween. The skeletonincludes a first helical member having a first proximally orientedsurface region and a first distally oriented surface region. A secondhelical member has a second proximally oriented surface region and asecond distally oriented surface region. The first and second helicalmembers have an overlap, and a first contraction offset can be definedbetween the first proximally oriented surface region of the first memberand the second distally oriented surface region of the second memberalong the overlap. An extension offset may be defined between the firstdistally oriented surface region of the first helical member and thesecond proximally oriented surface region of the second helical member.A first contraction balloon may be disposed in the first contractionoffset so that inflation of the first contraction balloon urges localaxial contraction of the skeleton. A first extension balloon can bedisposed in the first extension offset and in opposition to the firstballoon so that inflation of the extension balloon urges local axialextension of the skeleton and deflation of the first contractionballoon.

As a general feature, the helical members or elements of the skeletonsor frames included in the elongate articulating devices described hereinmay benefit from loop sections that have significant local stiffness(for example, with a channel shape that can transmit balloon engagementforces axially to axially adjacent frame loops or other structureswithout excessive local deformation of the channel cross-section), andalso from significant axial and/or lateral flexibility (for example, soas to accommodate differential axial expansion states of balloons andassociated axial elongation states of adjacent loop segments around thecircumference of the loop, and/or to accommodate lateral bending of theoverall frame along the axis). In related aspects, the helical membersor elements of the skeletons or frames described herein may benefit fromopenings to enhance flexibility, such as openings extending radiallythrough the walls or axially through the flanges or both, the openingsideally being disposed circumferentially between adjacent balloons. Suchopenings may, for example, be formed by cutting opposed angled orrounded notches through proximal end distal flanges of a helical channelmember, with the notches extending axially from the flanges toward eachother along a wall extending between the flanges. This may facilitatebending of the helical channel at the narrowed section of the wall,enhancing axial flexibility of the skeleton. Similar benefits may beprovided by including local or orientation-specific stiffeningstructures extending along a frame channel cross-section or the like.With or without such openings or stiffeners, exemplary helical framemembers may be fabricated by deposition of a polymer such as parylene ona metal mold. The flanges and walls of one or more helical frame memberincluded in the articulating devices described herein may be integrallyformed by such paralyene deposition, with the walls and flanges of theframes optionally having a thickness in a range from about 0.002″ toabout 0.010″. Alternative methods for integrally forming the flanges andwall of a channel member may comprise extruding a straight channel shapeand post-processing the straight extrusion by heating and bending theextrusion to a helical shape around an inner mandrel, ideally withsuitable support inside and outside the channel so as to provide thedesired helical shape and channel cross section.

In a still further aspect, the invention provides a method forarticulating an elongate flexible device. The method comprises directingfluid distally along an elongate flexible body of the device, the devicehaving a plurality of fluid expandable bodies distributed along andabout an axis extending along the body, wherein the fluid is directedtoward a subset of the fluid expandable bodies so as to expand theexpandable bodies of the subset. The elongate body adjacent theexpandable bodies of the subset locally contracts in response toexpanding of the expandable bodies of the subset so as to urge thedevice to bend laterally toward the subset, to decrease in axial length,to increase in lateral bending stiffness, or a combination thereof.

In a still further aspect, the invention provides a method for making anelongate flexible device. The method comprises forming at least oneelongate skeleton having a proximal end and a distal end and defining anaxis therebetween, the skeleton including a first surface and a secondsurface opposed to the first surface. The opposed surfaces are orientedprimarily axially. A fluid pathway is provided from the proximal end toa plurality of axial contraction balloons disposed radially between theinner wall and the outer wall, and axially between the first flange andthe second flange. The balloons and fluid conduit are arranged so that,in use, inflation of the contraction balloons via the pathway locallyurges the skeleton adjacent the inflated contraction balloons to axiallycontract. Optionally, the forming of the skeleton is performed bydeposition of parylene.

In yet another aspect, the invention provides an articulable systemcomprising an elongate flexible structural skeleton having a proximalend and a distal end with an axis extending therebetween. The skeletoncomprises a plurality of members extending primarily circumferentiallyabout the axis, the members having flanges extending primarily radiallyfrom walls extending primarily axially. Adjacent flanges of adjacentmembers are separated by local offsets that vary with lateral bending ofthe skeleton or axial elongation of the skeleton or both. A plurality offluid expandable bodies are disposed in the offsets of the skeleton andare configured to couple with a fluid supply system. This allows asubset of the expandable bodies to selectably expand so as to alter abend state of the axis, an elongation state of the axis, a lateralbending stiffness of the axis, or a combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified perspective view of a medical procedure in whicha physician can input commands into a catheter system so that a catheteris articulated using systems and devices described herein.

FIG. 1-1 schematically illustrates a catheter articulation system havinga hand-held proximal housing and a catheter with a distal articulatableportion in a relaxed state.

FIGS. 1A-1C schematically illustrate a plurality of alternativearticulation states of the distal portion of the catheter in the systemof FIG. 1.

FIG. 2 schematically illustrates an alternative distal structure havinga plurality of articulatable sub-regions or segments so as to provide adesired total number of degrees of freedom and range of movement.

FIG. 3 is a simplified exploded perspective view showing a balloon arraythat can be formed in a substantially planar configuration and rolledinto a cylindrical configuration, and which can be mounted coaxially toa helical coil or other skeleton framework for use in the catheter ofthe system of FIGS. 1 and 2.

FIGS. 4A and 4B are a simplified cross-section and a simplifiedtransverse cross-section, respectively, of an articulatable catheter foruse in the system of FIG. 1, shown here with the balloons of the arrayin an uninflated, small axial profile configuration and between loops ofthe coil.

FIG. 4C is a simplified transverse cross-section of the articulatablecatheter of FIGS. 4A and 4B, with a plurality of axially alignedballoons along one side of the articulatable region of the catheterinflated so that the catheter is in a laterally deflected state.

FIG. 4D is a simplified transverse cross-section of the articulatablecatheter of FIG. 4, with a plurality of laterally opposed balloonsinflated so that the catheter is in an axially elongated state.

FIG. 5 schematically illustrates components for use in the cathetersystem of FIG. 1, including the balloon array, inflation fluid source,fluid control system, and processor.

FIG. 5A is a simplified schematic of an alternative balloon array andfluid control system, in which a plurality of valves coupled with theproximal end of the catheter can be used to direct fluid to any of aplurality of channels of the array and thereby selectably determine asubset of balloons to be expanded.

FIG. 6 schematically illustrates a catheter articulation system in whichan input of the system is incorporated with an introducer sheath.

FIGS. 7 and 8 schematically illustrate balloon arrays in which theballoons are disposed over multi-lumen helical coil cores shafts orconduits, and also show the effects of varying balloon inflation densityon a radius of curvature of a catheter or other flexible body.

FIGS. 9-11 illustrate components of an alternative embodiment having aplurality of interleaved multi-lumen polymer helical cores interleavedwith a plurality of resilient coil structures having axially orientedsurfaces configured to radially restrain the balloons.

FIG. 12 is a perspective view of an alternative helical balloon corehaving a radially elongate cross-section to limit inflation fluid flowsand provide additional fluid channels and/or channel sizes.

FIGS. 13-17 schematically illustrate skeletons structures having framesor members with balloons mounted in opposition so as to axially extendwith inflation of one subset of the balloons, and to axially contractwith inflation of another subset of balloons.

FIGS. 18 and 19 are a schematic illustration of an exemplary axialexpansion/contraction skeleton with axial expansion and axialcontraction balloons; and a corresponding cross-section of a skeletonhaving an axial series of annular members or rings articulated by theaxial expansion and axial contraction balloons, respectively.

FIGS. 20-22B are illustrations of elongate flexible articulatedstructures having annular skeletons with three opposed sets of balloons,and show how varying inflation of the balloons can be used to axiallycontract some portions of the frame and axially extend other portions tobend or elongate the frame and to control a pose or shape of the framein three dimensions.

FIGS. 23A-23J are illustrations of alternative elongate articulatedflexible structures having annular skeletons and two sets of opposedballoons, and show how a plurality of independently controllable axialsegments can be combined to allow control of the overall elongatestructure with 6 or more degrees of freedom.

FIGS. 24A-24G illustrate components of another alternative elongatearticulated flexible structure having axial expansion balloons andopposed axial contraction balloons, the structures here having helicalskeleton members and helical balloon assemblies.

FIGS. 25A-25F illustrate exemplary elongate articulated flexiblestructures having helical skeleton members and three helical balloonassemblies supported in opposition along the skeleton, and also show howselective inflation of subsets of the balloons can locally axiallyelongate and/or contract the skeleton to bend the structure laterallyand/or alter the overall length of the structure.

FIGS. 26A and 26B illustrate alternative articulated structures similarto those of FIG. 25, here with two balloon assemblies supported inopposition along the frames.

FIG. 27 illustrates alternative multi-lumen conduit or core structuresfor use in the balloon assemblies of FIGS. 24 and 25, showing a varietyof different numbers of channels that can be used with different numbersof articulated segments.

FIGS. 28-33 schematically illustrate alternative helical framestructures having cuts and channels to enhance flexibility and/orprovide access to balloon end surfaces to promote rotational alignmentof subsets of balloons.

FIGS. 34, 35, and 36 illustrate components that may be used to helppromote rotational alignment of balloons along a helical balloon arraywithin helical or ring frame structures.

FIGS. 37 and 38 schematically illustrate an alternative helical innerframe having enhanced flexibility.

FIGS. 39A-39D illustrate alternative ring frame assemblies andcomponents.

DETAILED DESCRIPTION OF THE INVENTION

The catheter bodies (and many of the other elongate flexible bodies thatbenefit from the inventions described herein) will often be describedherein as having or defining an axis, such that the axis extends alongthe elongate length of the body. As the bodies are flexible, the localorientation of this axis may vary along the length of the body, andwhile the axis will often be a central axis defined at or near a centerof a cross-section of the body, eccentric axes near an outer surface ofthe body might also be used. It should be understood, for example, thatan elongate structure that extends “along an axis” may have length thatextends in an orientation with a significant axial component, but thelength of that structure need not be precisely parallel to the axis.Similarly, an elongate structure that extends “primarily along the axis”and the like will generally have a length that extends along anorientation that has a greater axial component than components in otherorientations orthogonal to the axis. Other orientations may be definedrelative to the axis of the body, including orientations that aretransvers to the axis (which will encompass orientation that generallyextend across the axis, but need not be orthogonal to the axis),orientations that are lateral to the axis (which will encompassorientations that having a significant radial component relative to theaxis), orientations that are circumferential relative to the axis (whichwill encompass orientations that extend around the axis. Theorientations of surfaces may be described herein by reference to thenormal of the surface extending away from the structure underlying thesurface. As an example, in a simple, solid cylindrical body that has anaxis that extends from a proximal end of the body to the distal end ofthe body, the distal-most end of the body may be described as beingdistally oriented, the proximal end may be described as being proximallyoriented, and the surface between the proximal and distal ends may bedescribed as being radially oriented. As another example, an elongatehelical structure extending axially around the above cylindrical body,with the helical structure comprising a wire with a square cross sectionwrapped around the cylinder at a 20 degree angle, might be describedherein as having two opposed axial surfaces (with one being primarilyproximally oriented, one being primarily distally oriented). Theoutermost surface of that wire might be described as being orientedexactly radially outwardly, while the opposed inner surface of the wiremight be described as being oriented radially inwardly, and so forth.

Embodiments provided herein may use balloon-like structures to effectarticulation of the elongate catheter or other body. The term“articulation balloon” may be used to refer to a component which expandson inflation with a fluid and is arranged so that on expansion theprimary effect is to cause articulation of the elongate body. Note thatthis use of such a structure is contrasted with a conventionalinterventional balloon whose primary effect on expansion is to causesubstantial radially outward expansion from the outer profile of theoverall device, for example to dilate or occlude or anchor in a vesselin which the device is located. Independently, articulated medialstructures described herein will often have an articulated distalportion, and an unarticulated proximal portion, which may significantlysimplify initial advancement of the structure into a patient usingstandard catheterization techniques.

Referring first to FIG. 1, a first exemplary catheter system 1 andmethod for its use are shown. A physician or other system user Uinteracts with catheter system 1 so as to perform a therapeutic and/ordiagnostic procedure on a patient P, with at least a portion of theprocedure being performed by advancing a catheter 3 into a body lumenand aligning an end portion of the catheter with a target tissue of thepatient. More specifically, a distal end of catheter 3 is inserted intothe patient through an access site A, and is advanced through one of thelumen systems of the body (typically the vasculature network) while userU guides the catheter with reference to images of the catheter and thetissues of the body obtained by a remote imaging system.

Exemplary catheter system 1 will often be introduced into patient Pthrough one of the major blood vessels of the leg, arm, neck, or thelike. A variety of known vascular access techniques may also be used, orthe system may alternatively be inserted through a body orifice orotherwise enter into any of a number of alternative body lumens. Theimaging system will generally include an image capture system 7 foracquiring the remote image data and a display D for presenting images ofthe internal tissues and adjacent catheter system components. Suitableimaging modalities may include fluoroscopy, computed tomography,magnetic resonance imaging, ultrasonography, combinations of two or moreof these, or others.

Catheter 3 may be used by user U in different modes during a singleprocedure. Catheter 3 may, for example, be manually advanced over aguidewire, using either over-the-wire or rapid exchange techniques.Catheter 3 may also be self-guiding during manual advancement (so thatfor at least a portion of the advancement of catheter 3, a distal tip ofthe catheter may guide manual distal advancement). In addition to suchmanual movement modes, catheter system 1 may also have a 3-D automatedmovement mode using computer controlled articulation of at least aportion of the length of catheter 3 disposed within the body of thepatient to change the shape of the catheter portion, often to advance orposition the distal end of the catheter. Still further modes ofoperation of system 1 may also be implemented, including concurrentmanual manipulation with automated articulation, for example, with userU manually advancing the proximal shaft through access site A whilecomputer-controlled lateral deflections and/or changes in stiffness overa distal portion of the catheter help the distal end follow a desiredpath or reduce resistance to the axial movement.

Referring next to FIG. 1-1 components which may be included in or usedwith catheter system 1 or catheter 3 (described above) can be more fullyunderstood with reference to an alternative catheter system 10 and itscatheter 12. Cather 12 generally includes an elongate flexible catheterbody and is detachably coupled to a handle 14, preferably by aquick-disconnect coupler 16. Catheter body 12 has an axis 30, and aninput 18 of handle 14 can be moved by a user so as to locally alter theaxial bending characteristics along catheter body 12, often for variablyarticulating an actuated portion 20 of the catheter body. Catheter body12 will often have a working lumen 26 into or through which atherapeutic and/or diagnostic tool may be advanced from a proximal port28 of handle 14. Alternative embodiments may lack a working lumen, mayhave one or more therapeutic or diagnostic tools incorporated into thecatheter body near or along actuated portion 20, may have a sufficientlysmall outer profile to facilitate use of the body as a guidewire, maycarry a tool or implant near actuated portion 20 or near distal end 26,or the like. In particular embodiments, catheter body 12 may support atherapeutic or diagnostic tool 8 proximal of, along the length of,and/or distal of actuated portion 20. Alternatively, a separate elongateflexible catheter body may be guided distally to a target site oncecatheter body 20 has been advanced (with the elongate body for such usesoften taking the form and use of a guidewire or guide catheter).

The particular tool or tools included in, advanceable over, and/orintroducible through the working lumen of catheter body 20 may includeany of a wide range of therapeutic and/or treatment structures. Examplesinclude cardiovascular therapy and diagnosis tools (such as angioplastyballoons, stent deployment balloons or other devices, atherectomydevices, tools for detecting, measuring, and/or characterizing plaque orother occlusions, tools for imaging or other evaluation of, and/ortreatment of, the coronary or peripheral arteries, structural hearttools (including prostheses or other tools for valve procedures, foraltering the morphology of the heart tissues, chambers, and appendages,and the like), tools for electrophysiology mapping or ablation tools,and the like); stimulation electrodes or electrode implantation tools(such as leads, lead implant devices, and lead deployment systems,leadless pacemakers and associated deployments systems, and the like);neurovascular therapy tools (including for accessing, diagnosis and/ortreatment of hemorrhagic or ischemic strokes and other conditions, andthe like); gastrointestinal and/or reproductive procedure tools (such ascolonoscopic diagnoses and intervention tools, transurethral proceduretools, transesophageal procedure tools, endoscopic bariatric proceduretools, etc.); hysteroscopic and/or falloposcopic procedure tools, andthe like; pulmonary procedure tools for therapies involving the airwaysand/or vasculature of the lungs; tools for diagnosis and/or treatment ofthe sinus, throat, mouth, or other cavities, and a wide variety of otherendoluminal therapies and diagnoses structures. Such tools may make useof known surface or tissue volume imaging technologies (includingimaging technologies such as 2-D or 3-D cameras or other imagingtechnologies; optical coherence tomography technologies; ultrasoundtechnologies such as intravascular ultrasound, transesophogealultrasound, intracardiac ultrasound, Doppler ultrasound, or the like;magnetic resonance imaging technologies; and the like), tissue or othermaterial removal, incising, and/or penetrating technologies (such arotational or axial atherectomy technologies; morcellation technologies;biopsy technologies; deployable needle or microneedle technologies;thrombus capture technologies; snares; and the like), tissue dilationtechnologies (such as compliant or non-compliant balloons, plasticallyor resiliently expandable stents, reversibly expandable coils, braids orother scaffolds, and the like), tissue remodeling and/or energy deliverytechnologies (such as electrosurgical ablation technologies, RFelectrodes, microwave antennae, cautery surfaces, cryosurgicaltechnologies, laser energy transmitting surfaces, and the like), localagent delivery technologies (such as drug eluting stents, balloons,implants, or other bodies; contrast agent or drug injection ports;endoluminal repaving structures; and the like), implant and prosthesisdeploying technologies, anastomosis technologies and technologies forapplying clips or sutures, tissue grasping and manipulationtechnologies; and/or the like. In some embodiments, the outer surface ofthe articulation structure may be used to manipulate tissues directly.Non-medical embodiments may similarly have a wide range of tools orsurfaces for industrial, assembly, imaging, manipulation, and otheruses.

Addressing catheter body 12 of system 10 (and particularly articulationcapabilities of actuated portion 20) in more detail, the catheter bodygenerally has a proximal end 22 and a distal end 24 with axis 30extending between the two. As can be understood with reference to FIG.2, catheter body 12 may have a short actuated portion 20 of about 3diameters or less, but will often have an elongate actuated portion 20extending intermittently or continuously over several diameters of thecatheter body (generally over more than 3 diameters, often over morethan 10 diameters, in many cases over more than 20 diameters, and insome embodiments over more than 40 diameters). A total length ofcatheter body 12 (or other flexible articulated bodies employing theactuation components described herein) may be from 5 to 500 cm, moretypically being from 15 to 260 cm, with the actuated portion optionallyhaving a length of from 1 to 150 cm (more typically being 2 to 20 cm)and an outer diameter of from 0.65 mm to 5 cm (more typically being from1 mm to 2 cm). Outer diameters of guidewire embodiments of the flexiblebodies may be as small as 0.012″ though many embodiments may be morethan 2 Fr, with catheter and other medical embodiments optionally havingouter diameters as large as 34 French or more, and with industrialrobotic embodiments optionally having diameters of up to 1″ or more.Exemplary catheter embodiments for structural heart therapies (such astrans-catheter aortic or mitral valve repair or implantation, leftatrial appendage closure, and the like) may have actuated portions withlengths of from 3 to 30 cm, more typically being from 5 to 25 cm, andmay have outer profiles of from 10 to 30 Fr, typically being from 12 to18 Fr or 12 to 26 Fr, and ideally being from 13 to 16 Fr or 18 to 24 Fr.Electrophysilogy therapy catheters (including those having electrodesfor sensing heart cycles and/or electrodes for ablating selected tissuesof the heart) may have sizes of from about 5 to about 12 Fr, andarticulated lengths of from about 3 to about 30 cm. A range of othersizes might also be implemented for these or other applications.

Referring now to FIGS. 1A, 1B, and 1C, system 10 may be configured toarticulate actuated portion 20. Articulation will often allow movementcontinuously throughout a range of motion, though some embodiments mayprovide articulation in-part or in-full by selecting from among aplurality of discrete articulation states. Catheters having opposedaxial extension and contraction actuators are described herein that maybe particularly beneficial for providing continuous controlled andreversible movement, and can also be used to modulate the stiffness of aflexible structure. These continuous and discrete systems share manycomponents (and some systems might employ a combination of bothapproaches). First addressing the use of a discrete state system, FIG.1A, system 10 can, for example, increase an axial length of actuatedportion 20 by one or more incremental changes in length ΔL. An exemplarystructure for implementation of a total selectable increase in length ΔLcan combine a plurality of incremental increases in length ΔL=ΔL₁+ΔL₂+ .. . ), as can be understood with reference to FIG. 4D. As shown in FIGS.1B and 1C, system 10 may also deflect distal end 24 to a first bentstate having a first bend angle 31 between unarticulated axis 30 and anarticulated axis 30′ (as shown schematically in FIG. 1B), or to a secondbent state having a total bend angle 33 (between articulated axis 30 andarticulated axis 30″), with this second bend angle being greater thanthe first bend angle (as shown schematically in FIG. 1C). An exemplarystructure for combining multiple discrete bend angle increments to forma total bend angle 33 can be understood with reference to FIG. 4C.Regardless, the additional total cumulative bend angle 33 may optionallybe implemented by imposing the first bend 31 (of FIG. 1B) as a firstincrement along with one or more additional bend angle increments 35.The incremental changes to actuated portion 20 may be provided by fullyinflating and/or deflating actuation balloons of the catheter system.Bend capabilities may be limited to a single lateral orientation, butwill more typically be available in different lateral orientations, mosttypically in any of 3 or 4 orientations (for example, using balloonspositioned along two pairs of opposed lateral axes, sometimes referredto as the +X, −X, +Y and −Y orientations), and by combining differentbend orientations, in intermediate orientations as well. Continuouspositioning may be implemented using similar articulation structures bypartially inflating or deflating balloons or groups of balloons.

System 10 may also be configured to provide catheter 12 with any of aplurality of discrete alternative total axial lengths. As with the bendcapabilities, such length actuation may also be implemented by inflatingballoons of a balloon array structure. To provide articulation with thesimple balloon array structures described herein, each actuation may beimplemented as a combination of discrete, predetermined actuationincrements (optionally together with one or more partial or modulatedactuation) but may more often be provided using modulated or partialinflation of balloons.

Referring now to FIGS. 1-1 and 2, embodiments of articulation system 10will move the distal end 24 of catheter 12 toward a desired positionand/or orientation in a workspace relative to a base portion 21, withthe base portion often being adjacent to and proximal of actuatedportion 20. Note that such articulation may be relatively (or evencompletely) independent of any bending of catheter body 12 proximal ofbase portion 21. The location and orientation of proximal base 21(relative to handle 14 or to another convenient fixed or movablereference frame) may be identified, for example, by including knowncatheter position and/or orientation identification systems in system10, by including radiopaque or other high-contrast markers andassociated imaging and position and/or orientation identifying imageprocessing software in system 10, by including a flexible body statesensor system along the proximal portion of catheter body 12, byforegoing any flexible length of catheter body 12 between proximalhandle 14 and actuated portion 20, or the like. A variety of differentdegrees of freedom may be provided by actuated portion 20. Exemplaryembodiments of articulation system 10 may allow, for example, distal end24 to be moved with 2 degrees of freedom, 3 degrees of freedom, 4degrees of freedom, 5 degrees of freedom, or 6 degrees of freedomrelative to base portion 21. The number of kinematic degrees of freedomof articulated portion 20 may be much higher in some embodiments,particularly when a number of different alternative subsets of theballoon array could potentially be in different inflation states to givethe same resulting catheter tip and/or tool position and orientation.

Note that the elongate catheter body 12 along and beyond actuatedportion 20 may (and often should) remain flexible before, during, andafter articulation, so as to avoid inadvertently applying lateral and/oraxial forces to surrounding tissues that are beyond a safe threshold.Nonetheless, embodiments of the systems described herein may locally andcontrollable increase a stiffness of one or more axial portions ofcatheter body 12, along actuated portion 20, proximal of actuatedportion 20, and/or distal of actuated portion 20. Such selectivestiffening of the catheter body may be implemented with or withoutactive articulation capabilities, may extend along one or more axialportion of catheter body 12, and may alter which portions are stiffenedand which are more flexible in response to commands from the user,sensor input (optionally indicating axial movement of the catheter), orthe like.

As shown in FIG. 2, actuated portion 20 may comprise an axial series of2 or more (and preferably at least 3) actuatable sub-portions orsegments 20′, 20″, 20′″, with the segments optionally being adjacent toeach other, or alternatively separated by relatively short (less than 10diameters) and/or relatively stiff intermediate portions of catheter 12.Each sub-portion or segment may have an associated actuation array, withthe arrays working together to provide the desired overall cathetershape and degrees of freedom to the tip or tool. At least 2 of thesub-portions may employ similar articulation components (such as similarballoon arrays, similar structural backbone portions, similar valvesystems, and/or similar software). Commonality may include the use ofcorresponding actuation balloon arrays, but optionally with thecharacteristics of the individual actuation balloons of the differentarrays and the spacing between the locations of the arrays varying forany distal tapering of the catheter body. There may be advantages to theuse of differentiated articulation components, for example, withproximal and distal sub portions, 20′, 20′″ having similar structuresthat are configured to allow selective lateral bending with at least twodegrees of freedom, and intermediate portion 20″ being configured toallow variable axial elongation. In many embodiments, however, at leasttwo (and preferabley all) segments are substantially continuous andshare common components and geometries, with the different segmentshaving separate fluid channels and being separately articulatable buteach optionally providing similar movement capabilities.

For those elongate flexible articulated structures described herein thatinclude a plurality of axial segments, the systems will often determineand implement each commanded articulation of a particular segment as asingle consistent articulation toward a desired segment shape state thatis distributed along that segment. In some exemplary embodiments, thenominal or resting segment shape state may be constrained to a 3 DOFspace (such as by continuous combinations of two transverse lateralbending orientations and an axial (elongation) orientation in an X-Y-Zwork space). In some of the exemplary embodiments described herein(including at least some of the helical extension/contractionembodiments), lateral bends along a segment may be at leastapproximately planar when the segment is in or near a design axiallength configuration (such as at or near the middle of the axial or Zrange of motion), but may exhibit a slight but increasing off-planetwisting curvature as the segment moves away from that designconfiguration (such as near the proximal and/or distal ends of the axialrange of motion). The off-plane bending may be repeatably accounted forkinematically by determining the changes in lateral orientation ofeccentric balloons resulting from winding and unwinding of helicalstructures supporting those balloons when the helical structuresincrease and decrease in axial length. For example, a segment may becommanded (as part of an overall desired pose or movement) to bend in a−Y orientation with a 20 degree bend angle. If the bend is to occur at adesign axial length (such as at the middle of the axial range ofmotion), and assuming balloons (or opposed balloon pairs) at 4 axialbend locations can be used to provide the commanded bend, the balloons(or balloon pairs) may each be inflated or deflated to bend the segmentby about 5 degrees (thereby providing a total bend of 5*4 or 20 degrees)in the −Y orientation. If the same bend is to be combined with axiallengthening of the segment to the end of its axial range of motion, theprocessor may determine that the segment may would exhibit some twist(say 2 degrees) so that there would be a slight +X component to thecommanded bend, so that the processor may compensate for the twist bycommanding a corresponding −X bend component, or by otherwisecompensating in the command for another segment of the flexible body.

Referring to FIGS. 3 and 5, catheter body 12 of system 10 includes anactuation array structure 32 mounted to a structural skeleton (here inthe form of a helical coil 34). Exemplary balloon array 32 includesfluid expandable structures or balloons 36 distributed at balloonlocations along a flexible substrate 38 so as to define an M×N array, inwhich M is an integer number of balloons distributed about acircumference 50 of catheter 12 at a given location along axis 30, and Nrepresents an integer number of axial locations along catheter 12 havingactuation balloons. Circumferential and axial spacing of the arrayelement locations will generally be known, and will preferably beregular. This first exemplary actuation array includes a 4×4 array for atotal of 16 balloons; alternative arrays may be from 1×2 arrays for atotal of 2 balloons to 8×200 arrays for a total of 1600 balloons (orbeyond), more typically having from 3×3 to 6×20 arrays. While balloonarrays of 1×N may be provided (particularly on systems that rely onrotation of the catheter body to orient a bend), M will more typicallybe 2 or more, more often being from 3 to 8, and preferably being 3 or 4.Similarly, while balloon arrays of M×1 may be provided to allowimposition of a single bend increment at a particular location in any ofa number of different desired lateral orientations, array 32 will moretypically have an N of from 2 to 200, often being from 3 to 20 or 3 to100. In contraction/expansion embodiments described below, multiplearrays may be provided with similar M×N arrays mounted in opposition.Not all array locations need have inflatable balloons, and the balloonsmay be arranged in more complex arrangements, such as with alternatingcircumferential numbers of balloons along the axis, or with varying oralternating separation between balloons along the axial length of thearray.

The balloons of a particular segment or that are mounted to a commonsubstrate may be described as forming an array, with the actuationballoon array structure optionally being used as a sub-array in amulti-segment or opposed articulation system. The combined sub-arraystogether may form an array of the overall device, which may also bedescribed simply as an array or optionally an overall or combined array.Exemplary balloon arrays along a segment or sub-portion of articulatedportion 20 include 1×8, 1×12, and 1×16 arrays for bending in a singledirection (optionally with 2, 3, 4, or even all of the balloons of thesegment in fluid communication with a single common inflation lumen soas to be inflated together) and 4×4, 4×8, and 4×12 arrays for X-Ybending (with axially aligned groups of 2-12 balloons coupled with 4 ormore common lumens for articulation in the +X, −X, +Y, and −Yorientations). Exemplary arrays for each segment having the opposedextension/retraction continuous articulation structures described hereinmay be in the form of a 3×2N, 3×3N, 4×2N, or 4×3N balloons arrays, forexample, 3×2, 3×4, 3×6, 3×8, 3×10, 3×12, 3×14, and 3×16 arrays with 6 to48 balloons, with the 3 lateral balloon orientations separated by 120degrees about the catheter axis. Extension balloons will often beaxially interspersed with contraction balloons along each lateralorientation, with separate 3×N arrays being combined together in a 3×2Nextension/contraction array for the segment, while two extensionballoons may be positioned axially between each contraction balloon for3×3N arrangements. The contraction balloons may align axially and/or bein plane with the extension balloons they oppose, though it may beadvantageous in some embodiments to arrange opposed balloons offset froma planer arrangement, so that (for example) two balloons of one typebalance one balloon of the other , or vice versa. The extension balloonsalong each orientation of the segment may share a common inflation fluidsupply lumen while the contraction balloons of the segment for eachorientation similarly share a common lumen (using 6 fluid supply lumensper segment for both 3×2N and 3×3N arrays). An extension/contractioncatheter may have from 1 to 8 such segments along the articulatedportion, more typically from 1 to 5 segments, and preferably being 2 to4 segments. Other medical and non-medical elongate flexible articulatedstructures may have similar or more complex balloon articulation arrays.

As can be seen in FIGS. 3, 4A, 4B, and 4C, the skeleton will often(though not always) include an axial series of loops 42. When the loopsare included in a helical coil 34, the coil may optionally be biased soas to urge adjacent loops 42 of the coil 34 toward each other. Suchaxially compressive biasing may help urge fluid out and deflate theballoons, and may by applied by other structures (inner and/or outersheath(s), pull wires, etc.) with or without helical compression. Axialengagement between adjacent loops (directly, or with balloon walls orother material of the array between loops) can also allow compressiveaxial forces to be transmitted relatively rigidly when the balloons arenot inflated. When a particular balloon is fully inflated, axialcompression may be transmitted between adjacent loops by the fullyinflated balloon wall material and by the fluid within the balloons.Where the balloon walls are non-compliant, the inflated balloons maytransfer these forces relatively rigidly, though with some flexing ofthe balloon wall material adjacent the balloon/skeleton interface. Rigidor semi-rigid interface structures which distribute axial loads across abroader balloon interface region may limit such flexing. Axial tensionforces (including those associated with axial bending) may be resistedby the biasing of the skeleton (and/or by other axial compressivestructures). Alternative looped skeleton structures may be formed, forexample, by cutting hypotube with an axial series of lateral incisionsacross a portion of the cross-section from one or more lateralorientations, braided metal or polymer elements, or the like. Non-loopedskeletons may be formed using a number of alternative known rigid orflexible robotic linkage architectures, including with structures basedon known soft robot structures. Suitable materials for coil 34 or otherskeleton structures may comprise metals such as stainless steel, springsteel, superelastic or shape-memory alloys such as Nitinol™ alloys,polymers, fiber-reinforced polymers, high-density or ultrahigh-densitypolymers, or the like.

When loops are included in the skeleton, actuation array 32 can bemounted to the skeleton with at least some of the balloons 36 positionedbetween two adjacent associated loops 42, such as between the loops ofcoil 34. Referring now to FIG. 4C, an exemplary deflated balloon 36 i islocated between a proximally adjacent loop 42 i and a distally adjacentloop 42 ii, with a first surface region of the balloon engaging adistally oriented surface of proximal loop 34 i, and a second surfaceregion of the balloon engaging a proximally oriented surface of distalloop 42 ii. The walls of deflated balloon 36 i have some thickness, andthe proximal and distal surfaces of adjacent loops 42 i and 42 iimaintain a non-zero axial deflated offset 41 between the loops. Axialcompression forces can be transferred from the loops through the solidballoon walls. Alternative skeletal structures may allow the loops toengage directly against each other so as to have a deflated offset ofzero and directly transmit axial compressive force, for example byincluding balloon receptacles or one or more axial protrusions extendingfrom one or both loops circumferentially or radially beyond the balloonand any adjacent substrate structure. Regardless, full inflation of theballoon will typically increase the separation between the adjacentloops to a larger full inflation offset 41′. The simplified lateralcross-sections of FIGS. 4B, 4C, and 4D schematically show a directinterface engagement between a uniform thickness thin-walled balloon anda round helical coil loop. Such an interface may result in relativelylimited area of the balloon wall engaging the coil and associateddeformation under axial loading. Alternative balloon-engaging surfaceshapes along the coils (often including locally increased convex radii,locally flattened surfaces, and/or local concave balloon receptacles)and/or along the coil-engaging surfaces of the balloon (such as bylocally thickening the balloon wall to spread the engagement area),and/or providing load-spreading bodies between the balloons and thecoils may add axial stiffness. A variety of other modifications to theballoons and balloon/coil interfaces may also be beneficial, includingadhesive bonding of the balloons to the adjacent coils, including foldsor material so as to inhibit balloon migration, and the like.

Inflation of a balloon can alter the geometry along catheter body 12,for example, by increasing separation between loops of a helical coil soas to bend axis 30 of catheter 12. As can be understood with referenceto FIGS. 1B, 1C and 4-4C, selectively inflating an eccentric subset ofthe balloons can variably alter lateral deflection of the catheter axis.As can be understood with reference to FIGS. 1A, 4, and 4D, inflation ofall (or an axisymmetric subset) of the balloons may increase an axiallength of the catheter structure. Inflating subsets of the balloons thathave a combination of differing lateral orientations and axial positionscan provide a broad range of potential locations and orientations of thecatheter distal tip 26, and/or of one or more other locations along thecatheter body (such as where a tool is mounted).

Some or all of the material of substrate 38 included in actuation array32 will often be relatively inelastic. It may, however, be desirable toallow the skeleton and overall catheter to flex and/or elongate axiallywith inflation of the balloons or under environmental forces. Hence,array 32 may have cutouts 56 so as to allow the balloon array to moveaxially with the skeleton during bending and elongation. The arraystructure could alternatively (or in addition) be configured for sucharticulation by having a serpentine configuration or a helical coiledconfiguration. Balloons 36 of array 32 may include non-compliant balloonwall materials, with the balloon wall materials optionally being formedintegrally from material of the substrate or separately. Note thatelastic layers or other structures may be included in the substrate foruse in valves and the like, and that some alternative balloons mayinclude elastic and/or semi-compliant materials.

Referring to FIGS. 3, 4A, and 5, substrate 38 of array 32 is laterallyflexible so that the array can be rolled or otherwise assume acylindrical configuration when in use. The cylindrical array may becoaxially mounted to (such as being inserted into or radially outwardlysurrounding) the helical coil 34 or other structural backbone of thecatheter. The cylindrical configuration of the array will generally havea diameter that is equal to or less than an outer diameter of thecatheter. The opposed lateral edges of substrate 38 may be separated bya gap as shown, may contact each other, or may overlap. Contacting oroverlapping edges may be affixed together (optionally so as to help sealthe catheter against radial fluid flow) or may accommodate relativemotion (so as to facilitate axil flexing). In some embodiments, lateralrolling or flexing of the substrate to form the cylindricalconfiguration may be uniform (so as to provide a continuous lateralcurve along the major surfaces), while in other embodiments intermittentaxial bend regions of the substrate may be separated by axially elongaterelatively flat regions of the substrate so that a cylindrical shape isapproximated by a prism-like arrangement (optionally so as to limitbending of the substrate along balloons, valves, or other arraycomponents).

It will often (though not always) be advantageous to form and/orassemble one or more components of the array structure in a flat,substantially planar configuration (and optionally in a linearconfiguration as described below). This may facilitate, for example,partial or final formation of balloons 36 on substrate 38, oralternatively, attachment of pre-formed balloons to the substrate. Theflat configuration of the substrate may also facilitate the use of knownextrusion or microfluidic channel fabrication techniques to providefluid communication channels 52 so as to selectively couple the balloonswith a fluid inflation fluid source or reservoir 54, and the like. Stillfurther advantages of the flat configuration of the substrate mayinclude the use of electrical circuit printing techniques to fabricateelectrical traces and other circuit components, automated 3-D printingtechniques (including additive and/or removal techniques) for formingvalves, balloons, channels, or other fluid components that will besupported by substrate 38, and the like. When the substrate is in arolled, tubular, or flat planar configuration, the substrate willtypically have a first major surface 62 adjacent balloons 36, and asecond major surface 64 opposite the first major surface (with firstmajor surface 62 optionally being a radially inner or outer surface andsecond major surface 64 being a radially outer or inner surface,respectively, in the cylindrical configuration). To facilitate flexingsubstrate 38 and array 32 into the rolled configuration, relief cuts orchannels may be formed extending into the substrate from the firstand/or second major surfaces, or living hinge regions may otherwise beprovided between relatively more rigid portions of the substrate. Tofurther avoid deformation of the substrate adjacent any valves or othersensitive structures, local stiffening reinforcement material may beadded, and/or relief cuts or apertures may be formed partiallysurrounding the valves. In some embodiments, at least a portion of thearray components may be formed or assembled with the substrate at leastpartially in a cylindrical configuration, such as by bonding layers ofthe substrate together while the substrate is at least locally curved,forming at least one layer of the substrate as a tube, selectivelyforming cuts in the substrate (optionally with a femtosecond,picosecond, or other laser) to form fluid, circuit, or other componentsor allow for axial flexing and elongation (analogous to cutting a stentto allow for axial flexing and radial expansion) and/or to form at leastsome of the channels, and bonding the layers together after cutting.

As can be understood with reference to FIGS. 5 and 5A, substrate 38 ofarray 32 may include one or more layers of flexible substrate material.The substrate layers may comprise known flexible and/or rigidmicrofluidic substrate materials, such as polydimethylsiloxane (PDMS),polyimide (PI), polyethylene (PE) and other polyolefins, polystyrene(PS), polyethylene terephthalate (PET), polypropylene (PP),polycarbonate (PC), nanocomposite polymer materials, glass, silicon,cyclic olefin copolymer (COC), polymethyl methacrylate (PMMA),polyetheretherketone (PEEK), polyester, polyurethane (PU), and/or thelike. These and still further known materials may be included in othercomponents of actuation array 32, including known polymers for use inballoons (which will often include PET, PI, PE, polyether block amide(PEBA) polymers such as PEBAX™ polymers, nylons, urethanes, polyvinylchloride (PVC), thermoplastics, and/or the like for non-compliantballoons; or silicone, polyurethane, semi-elastic nylons or otherpolymers, latex, and/or the like for compliant or semi-compliantballoons). Additional polymers than may be included in the substrateassembly may include valve actuation elements (optionally includingshape memory alloy structures or foils; phase-change actuator materialssuch as paraffin or other wax, electrical field sensitive hydrogels,bimetallic actuators, piezoelectric structures, dielectric elastomeractuator (DEA) materials, or the like). Hence, while some embodimentsmay employ homogenous materials for actuation array 32, many arrays andsubstrate may instead be heterogeneous.

Fortunately, techniques for forming and assembling the components foractuation array 32 may be derived from a number of recent (andrelatively widely-reported) technologies. Suitable techniques forfabricating channels in substrate layer materials may include lasermicromachining (optionally using femtosecond or picosecond lasers),photolithography techniques such as dry resist technologies, embossing(including hot roller embossing), casting or molding, xerographictechnologies, microthermoforming, stereolithography, 3-D printing,and/or the like. Suitable 3-D printing technologies that may be used toform circuitry, valves, sensors, and the like may includestereolithography, digital light processing, laser sintering or melting,fused deposition modeling, inkjet printing, selective depositionlamination, electron beam melting, or the like. Assembly of thecomponents of actuation array 32 may make use of thermal or adhesivebonding between layers and other components, though laser, ultrasound,or other welding techniques; microfasteners, or the like may also beused. Electrical element fabrication of conductive traces, actuation,signal processor, and/or sensor components carried by substrate 38 may,for example, use ink-jet or photolithography techniques, 3-D printing,chemical vapor deposition (CVD) and/or more specific variants such asinitiated chemical vapor deposition (iCVD), robotic microassemblytechniques, or the like, with the electrical traces and other componentsoften comprising inks and other materials containing metals (such assilver, copper, or gold) carbon, or other conductors. Many suitablefabrication and assembly techniques have been developed duringdevelopment of microfluidic lab-on-a-chip or lab-on-a-foil applications.Techniques for fabricating medical balloons are well developed, and mayoptionally be modified to take advantage of known high-volume productiontechniques (optionally including those developed for fabricating bubblewrap, for corrugating extruded tubing, and the like). Note that whilesome embodiments of the actuation array structures described herein mayemploy fluid channels sufficiently small for accurately handling ofpicoliter or nanoliter fluid quantities, other embodiments will includechannels and balloons or other fluid-expandable bodies that utilize muchlarger flows so as to provide desirable actuation response times.Balloons having at least partially flexible balloon walls may provideparticular advantages for the systems described herein, but alternativerigid fluid expandable bodies such as those employing pistons or otherpositive displacement expansion structures may also find use in someembodiments.

The structures of balloons 36 as included in actuation array 32 may beformed of material integral with other components of the array, or maybe formed separately and attached to the array. Balloons 36 may beformed from or attached to a first sheet of substrate material that canbe bonded or otherwise affixed to another substrate layer or layers. Thematerial of the balloon layer may optionally cover portions of thechannels directly, or may be aligned with apertures that open through anintermediate substrate layer surface between the channels and theballoons. Alternative methods for fabricating individual balloons arewell known, and the formed balloons may be affixed to the substrate 38by adhesive bonding. Balloon shapes may comprise relatively simplecylinders or may be somewhat tailored to taper to follow an expandedoffset between loops of a coil, to curve with the cylindrical substrateand/or to engage interface surfaces of the skeleton over a broadersurface area and thereby distribute actuation and environmental loads.Effective diameters of the balloons in the array may range from about0.003 mm to as much as about 2 cm (or more), more typically being in arange from about 0.3 mm to about 2 mm or 5 mm, with the balloon lengthsoften being from about 2 to about 15 times the diameter. Typical balloonwall thicknesses may range from about 0.0002 mm to about 0.004 mm (withsome balloon wall thicknesses being between 0.0002 mm and 0.020 mm), andfull inflation pressures in the balloons may be from about 0.2 to about40 atm, more typically being in a range from about 0.4 to about 30 atm,and in some embodiments being in a range from about 10 to about 30 atm,with high-pressure embodiments operating at pressures in a range as highas 20-45 atm and optionally having burst pressures of over 50 atm. Lowpressure embodiments may have semi-compliant or non-compliant balloonwall materials and inflation pressures in a range from about 0.3 atm toabout 11 atm.

Referring now to FIG. 5, balloons 36 will generally be inflated using afluid supply system that includes a fluid source 54 (shown here as apressurized single-use cartridge) and one or more valves 90. At leastsome of the valves 90 may be incorporated into the balloon arraysubstrate, with the valves optionally being actuated using circuitryprinted on one or more layers of substrate 38. With or withoutsubstrate-mounted valves that can be used within a patient body, atleast some of the valves may be mounted to housing 14, or otherwisecoupled to the proximal end of catheter 12. Valves 90 will preferably becoupled to channels 52 so as to allow the fluid system to selectivelyinflate any of a plurality of alternative individual balloons or subsetsof balloons 36 included in actuation array 32, under the direction of aprocessor 60. Hence, processor 60 will often be coupled to valves 90 viaconductors, the conductors here optionally including flex circuit traceson substrate 38.

Referring still to FIG. 5, fluid source 54 may optionally comprise aseparate fluid reservoir and a pump for pressurizing fluid from thereservoir, but will often include a simple tank or cartridge containinga pressurized fluid, the fluid optionally being a gas or a gas-liquidmixture. The cartridge will often maintain the fluid at a supplypressure at or above a full inflation pressure range of balloons 36,with the cartridge optionally being gently heated by a resistive heateror the like (not shown) in housing 14 so as to maintain the supplypressure within a desired range in the cartridge during use. Supplypressures will typically exceed balloon inflation pressures sufficientlyto provide balloon inflation times within a target threshold given thepressure loss through channels 52 and valves 90, with typical supplypressures being between 10 and 210 atm, and more typically being between20 and 60 atm. Suitable fluids may include known medical pressurizedgases such as carbon dioxide, nitrogen, oxygen, nitrous oxide, air,known industrial and cryogenic gasses such as helium and/or other inertor noble gasses, refrigerant gases including fluorocarbons, and thelike. Note that the pressurized fluid in the canister can be directedvia channels 52 into balloons 36 for inflation, or the fluid from thecanister (often at least partially a gas) may alternatively be used topressurize a fluid reservoir (often containing or comprising a benignbiocompatible liquid such as water or saline) so that the ballooninflation fluid is different than that contained in the cartridge. Wherea pressurized liquid or gas/liquid mixture flows distally along thecatheter body, enthalpy of vaporization of the liquid in or adjacent tochannels 52, balloons 36, or other tissue treatment tools carried on thecatheter body (such as a tissue dilation balloon, cryogenic treatmentsurface, or tissue electrode) may be used to therapeutically cooltissue. In other embodiments, despite the use of fluids which are usedas refrigerants within the body, no therapeutic cooling may be provided.The cartridge may optionally be refillable, but will often instead havea frangible seal so as to limit re-use.

As the individual balloons may have inflated volumes that are quitesmall, cartridges that are suitable for including in a hand-held housingcan allow more than a hundred, optionally being more than a thousand,and in many cases more than ten thousand or even a hundred thousandindividual balloon inflations, despite the cartridge containing lessthan 10 ounces of fluid, often less than 5 ounces, in most cases lessthan 3 ounces, and ideally less than 1 ounce. Note also that a number ofalternative fluid sources may be used instead of or with a cartridge,including one or more positive displacement pumps (optionally such assimple syringe pumps), a peristaltic or rotary pump, any of a variety ofmicrofluidic pressure sources (such as wax or other phase-change devicesactuated by electrical or light energy and/or integrated into substrate38), or the like. Some embodiments may employ a series of dedicatedsyringe or other positive displacement pumps coupled with at least someof the balloons by channels of the substrate, and/or by flexible tubing.

Referring still to FIG. 5, processor 60 can facilitate inflation of anappropriate subset of balloons 36 of actuation array 32 so as to producea desired articulation. Such processor-derived articulation cansignificantly enhance effective operative coupling of the input 18 tothe actuated portion 20 of catheter body 12, making it much easier forthe user to generate a desired movement in a desired direction or toassume a desired shape. Suitable correlations between input commands andoutput movements have been well developed for teleoperated systems withrigid driven linkages. For the elongate flexible catheters and otherbodies used in the systems described herein, it will often beadvantageous for the processor to select a subset of balloons forinflation based on a movement command entered into a user interface 66(and particularly input 18 of user interface 66), and on a spatialrelationship between actuated portion 20 of catheter 12 and one or morecomponent of the user interface. A number of differing correlations maybe helpful, including orientational correlation, displacementcorrelation, and the like. Along with an input, user interface 66 mayinclude a display showing actuated portion 20 of catheter body 12, andsensor 63 may provide signals to processor 60 regarding the orientationand/or location of proximal base 21. Where the relationship between theinput, display, and sensor are known (such as when they are all mountedto proximal housing 14 or some other common base), these signals mayallow derivation of a transformation between a user interface coordinatesystem and a base coordinate system of actuated portion 20. Alternativesystems may sense or otherwise identify the relationships between thesensor coordinate system, the display coordinate system, and/or theinput coordinate system so that movements of the input result incatheter movement, as shown in the display. Where the sensor comprisesan image processor coupled to a remote imaging system (such as afluoroscopy, MRI, or ultrasound system), high-contrast marker systemscan be included in proximal base 21 to facilitate unambiguousdetermination of the base position and orientation. A battery or otherpower source (such as a fuel cell or the like) may be included inhousing 14 and coupled to processor 60, with the housing and catheteroptionally being used as a handheld unit free of any mechanical tetherduring at least a portion of the procedure. Nonetheless, it should benoted that processor 60 and/or sensor 63 may be wirelessly coupled oreven tethered together (and/or to other components such as a separatedisplay of user interface 66, an external power supply or fluid source,or the like).

Regarding processor 60, sensor 63, user interface 66, and the other dataprocessing components of system 10, it should be understood that thespecific data processing architectures described herein are merelyexamples, and that a variety of alternatives, adaptations, andembodiments may be employed. The processor, sensor, and user interfacewill, taken together, typically include both data processing hardwareand software, with the hardware including an input (such as a joystickor the like that is movable relative to housing 14 or some other inputbase in at least 2 dimensions), an output (such as a medical imagedisplay screen), an image-acquisition device or other sensor, and one ormore processor. These components are included in a processor systemcapable of performing the image processing, rigid-body transformations,kinematic analysis, and matrix processing functionality describedherein, along with the appropriate connectors, conductors, wirelesstelemetry, and the like. The processing capabilities may be centralizedin a single processor board, or may be distributed among the variouscomponents so that smaller volumes of higher-level data can betransmitted. The processor(s) will often include one or more memory orstorage media, and the functionality used to perform the methodsdescribed herein will often include software or firmware embodiedtherein. The software will typically comprise machine-readableprogramming code or instructions embodied in non-volatile media, and maybe arranged in a wide variety of alternative code architectures, varyingfrom a single monolithic code running on a single processor to a largenumber of specialized subroutines being run in parallel on a number ofseparate processor sub-units.

Referring now to FIG. 5A, an alternative actuation array and fluidsupply system are shown schematically. As in the above embodiment,balloons 36 are affixed along a major surface of substrate 38,optionally prior to rolling the substrate and mounting of the actuationarray to the skeleton of the catheter body. In this embodiment, eachballoon has an associated dedicated channel 52 of substrate 38, and alsoan associated valve 90. Processor 60 is coupled with valves 90, and byactuating a desired subset of the valves the associated subset ofballoons can be inflated or deflated. In some embodiments, each valvecan be associated with more than one balloon 36, so that (for example),opening of a single valve might inflate a plurality (optionally 2, 3, 4,8, 12, or some other desired number) of balloons, such as laterallyopposed balloons so as to elongate the distal portion of the catheter.In these or other embodiments, a plurality of balloons (2, 3, 4, 5, 8,12, or another desired number) on one lateral side of the catheter couldbe in fluid communication with a single associated valve 90 via a commonchannel or multiple channels so that opening of the valve inflates theballoons and causes a multi-balloon and multi-increment bend in the axisof the catheter. Still further variations are possible. For example, insome embodiments, channels 52 may be formed at least in-part by flexibletubes affixed within an open or closed channel of substrate 38, or gluedalong a surface of the substrate. The tubes may comprise polymers (suchas polyimide, PET, nylon, or the like), fused silica, metal, or othermaterials, and suitable tubing materials may be commercially availablefrom Polymicro Technologies of Arizona, or from a variety of alternativesuppliers. The channels coupled to the proximal end of the actuatablebody may be assembled using stacked fluidic plates, with valves coupledto some or all of the plates. Suitable electrically actuated microvaluesare commercially available from a number of suppliers. Optionalembodiments of fluid supply systems for all balloon arrays describedherein may have all values mounted to housing 14 or some other structurecoupled to and/or proximal of) the proximal end of the elongate flexiblebody. Advantageously, accurately formed channels 52 (having sufficientlytight tolerance channel widths, depths, lengths, and/or bends or otherfeatures) may be fabricated using microfluidic techniques, and may beassembled with the substrate structure, so as to meter flow of theinflation fluid into and out of the balloons of all of the actuationarrays described herein.

A variety of known lab-on-a-chip and lab-on-a-foil production techniquescan be used to assemble and seal the substrate layers, with manyembodiments employing thermal fusion bonding, solvent bonding, welding(and particularly ultrasound welding), UV-curable adhesives, contactadhesives, nano-adhesives (including doubly cross-linked nano-adhesiveor DCNA), epoxy-containing polymers (including polyglycidylmethacrylate), plasma or other surface modifications, and/or the likebetween layers. For high fluid pressure systems, third generationnano-adhesive techniques such as CVD deposition of less than 400nanometer layers of DCNA materials may facilitate the use ofhigh-strength polymer materials such as PET. Channels of suchhigh-pressure systems may optionally be defined at least in part by PETand/or fused silica tubing (which may be supported by a substrate alongsome or all of the channel, and/or may be bundled together with otherfused silica tubing along some or all of its length ideally in anorganized array with tubing locations corresponding to the balloonlocations within the balloon array, analogous to the organization of acoherent fiber optic bundle), or the like. Any valves mounted to thesubstrate of the balloon array may be electrically actuated usingconductive traces deposited on a surface of a substrate layer prior tobonding, with an overlying layer sealing the traces in the interior ofthe substrate. Valve members may move when a potential is applied to anactuation material using the traces, with that material optionallycomprising a shape-memory alloy, piezoelectric, an electrically actuatedpolymer, or the like. Still further alternative actuation materials mayinclude phase change materials such as wax or the like, with the phasechange being induced by electrical energy or optical energy (such aslaser light transmitted via an optical fiber or printed pathway betweenlayers of the substrate). In some embodiments, the actuation materialand valve member may be formed using 3-D printing techniques. Multiplexcircuitry may be included in, deposited on a layer of, or affixed tosubstrate 38 so that the number of electrical traces extendingproximally along catheter body 12 may be less than the number of valvesthat can be actuated by those valves. The valves may take any of a widevariety of forms, and may employ (or be derived from) known valvestructures such as known electrostatically-actuated elastomericmicrofluidic valves, microfluidic polymer piston or free-floating gatevalves, layered modular polymeric microvalves, dielectric elastomeractuator valves, shape memory alloy microvalves, hydrogel microactuatorvalves, integrated high-pressure fluid manipulation valves employingparaffin, and the like. Along with electrically actuated microvalves,suitable valves may be optically actuated, fluid actuated, or the like.

It should be understood that many of the valves shown herein areschematic, and that additional or more complex valves and channelsystems may be included to control inflation and deflation of theballoons. One or more valves in the system may comprise gate valves(optionally normally closed, normally open or stable), so as to turninflation fluid flow from the fluid source to at least one balloon on oroff. Deflation may optionally be controlled by a separate gate valvebetween each balloon (or groups of balloons) and one or more deflationport of substrate 38 (the fluid from the balloon optionally exiting fromthe substrate to flow proximally between radially inner and outer sealedlayers of the catheter) or housing 14. Alternative 2-way valves mayallow i) communication between either the fluid source and the balloon(with flow from the balloon being blocked), or ii) between the balloonand the deflation outflow (with the flow from the fluid source beingblocked). Still further alternatives may be employed, including a 3 wayvalve having both of the above modes and iii) a sealed balloon mode inwhich the balloon is sealed from communication with the fluid source andfrom the deflation outflow (with flow from the source also beingclosed).

Referring now to FIG. 6, components of an exemplary catheterarticulation system 292 can be seen, with these components generallybeing suitable for use in catheter system 1 of FIG. 1. In thisembodiment, a catheter 294 has a distal articulated portion 296, withthe articulated portion optionally including axially separatearticulation sub-portions or segments, and alternatively having a singlerelatively continuously articulated length. An insertion sheath/inputassembly 295 is included in the system user interface, and both assembly295 and the proximal end of catheter 294 are detachably coupleable witha proximal housing 298 using flexible cables (and quick-disconnectcouplers), with the housing containing a battery, a processor, areplaceable compressed fluid cartridge, valves, and the like. Housing298 also includes or contains additional components of the userinterface, and is sized for positioning by a single hand of a user, butneed not be moved during use of catheter 294. Commands to effectautomated bending and elongation of distal portion 296 during use mayoptionally be input into the system by bending and axial insertion ofinput 297 relative to a proximal body of the introducer sheath, therebyemploying manual movements of the user which are already familiar tophysicians that employ catheter-based diagnostic and therapeutic tools.

Regarding some of the user interface components of articulation system292, use of input 297 for controlling the articulation state of catheter294 will be described in more detail hereinbelow. In addition to input297, a number of additional (or alternative) user interface componentsmay be employed. As generally indicated above, the user interface mayinclude a housing affixed to a proximal end of catheter 294, with thehousing having a joystick as described above regarding FIG. 1-1.Trackballs or touchpads may be provided in place of a joystick, and asthe catheters and other structures described herein may have more thantwo degrees of freedom, some embodiments may include two offsetjoysticks, with a more proximal joystick on the handle being used tolaterally deflect the catheter along a proximal X-Y segment and a moredistal joystick of the same handle being used to laterally deflect thecatheter along a more distal X′-Y′ segment. These two deflections may beused to enter movement commands in a manner analogous to positioning ofa robotic base using the first joystick and then articulating a wristmounted to that base with the second joystick, with the joysticksproviding either position or velocity control input to the cathetersystem. An input wheel with a surface that rolls along the axis of thehousing can be used for entering axial elongation movement commands, andthe housing may have a circumferential wheel that can be turned by thesystem user to help provide a desired alignment between an orientationof the housing relative to the lateral deflections of the catheter asseen in the remote imaging display. Still further alternative userinterface systems may employ computer workstations such as those ofknown robotic catheter or robotic surgical systems, which may includeone or more 3-D joysticks (optionally including an input allowing 4D,5D, or even more degrees of freedom), housings mimicking those ofmechanically steerable catheter systems, or the like. As seen in theembodiment of FIG. 6, still further optional components include atouchscreen (which may show a graphical representation of distalarticulated portion 296 (one or more segments of which can betouch-selected and highlighted so that they articulate in response tomovement of input 297), pushbuttons, or the like. Still furtheralternative user interface components may include voice control, gesturerecognition, stereoscopic glasses, virtual reality displays, and/or thelike.

Referring now to FIGS. 7 and 8, an alternative coaxial balloon/coilarrangement can be understood. In these embodiments, balloons 364 aremounted over a coil 366, with a plurality of the balloons typicallybeing formed from a continuous tube of material that extends along thehelical axis of the coil. The balloon material will generally have adiameter that varies locally, with the balloons being formed fromlocally larger diameter regions of the tube, and the balloons beingseparated by sealing engagement between the tube material and coiltherein at locally smaller diameters of the tube. The variation indiameter may be formed by locally blowing the balloons outward from aninitial tube diameter, by locally heat-shrinking and/or axiallystretching the tube down from an initial tube diameter, or both, andadhesive or heat-bonding between the tube and coil core therein mayenhance sealing. In alternative embodiments, metal rings may be crimpedaround the tubular balloon material to affix (and optionally seal) thetube to the underlying helical coil, with the rings and crimpingoptionally employing marker band structures and associated techniques.Some or even all of the variation in diameter of the balloon materialalong the coil may be imposed by the crimped rings, though selectiveheat shrinking and/or blowing of the balloons and/or laser thermalbonding of the balloon to the coil may be combined with the crimps toprovide the desired balloon shape and sealing. Regardless, fluidcommunication between the inner volume of the balloon (between theballoon wall and the coil core) may be provided through a radial port toan associated lumen within the coil core. As can be understood withreference to coil assembly 360 of FIG. 7, the balloons may have outersurface shapes similar to those described above, and may similarly bealigned along one or more lateral bending orientations. As can beunderstood with reference to assemblies 360 and 362 of FIGS. 7 and 8,bend angles and radii of curvature of the catheter adjacent the balloonarrays may be determined by an axial spacing (and/or number of loops)between balloons, and/or by selective inflation of a subset of balloons(such as by inflating every other balloon aligned along a particularlateral axis, every third aligned balloon, every forth aligned balloon,and so on).

Referring now to FIGS. 9-11, a still further embodiment of anarticulated catheter includes first and second interleaved helicalmulti-lumen balloon fluid supply/support structures 440 a, 440 b, alongwith first and second resilient helical coils 442 a, 442 b. In thisembodiment, a series of balloons (not shown) are mounted around each ofthe multi-lumen structures, with the balloons spaced so as to be alignedalong three lateral bending orientations that are offset from each otheraround the axis of the catheter by 120 degrees. Six lumens are providedin each multi-lumen structure, 440 a, 440 b, with one dedicatedinflation lumen and one dedicated deflation lumen for each of the threelateral bending orientations. Radial fluid communication ports betweenthe lumens and associated balloons may be provided by through cutsthrough pairs of the lumens.

By spacing the cuts 444 a, 444 b, 444 c, as shown, and by mountingballoons over the cuts, the inflation and deflation lumens can be usedto inflate and deflate a subset of balloons aligned along each of thethree bending orientations. Advantageously, a first articulated segmenthaving such a structure can allow bending of the catheter axis in anycombination of the three bend orientations by inflating a desired subsetof the balloons along that segment. Optionally, the bend angle for thatsubset may be controlled by the quantity and/or pressure of fluidtransmitted to the balloons using the 6 lumens of just one multi-lumenstructure (for example, 440 a), allowing the segment to function in amanner analogous to a robotic wrist. Another segment of the catheteraxially offset from the first segment can have a similar arrangement ofballoons that are supplied by the 6 lumens of the other multi-lumenstructure (in our example, 440 b), allowing the catheter to position andorient the end of the catheter with flexibility analogous to that of aserial wrist robotic manipulators. In other embodiments, at least someof the balloons supplied by the two multi-lumen structures may axiallyoverlap, for example, to allow increasing bend angles and/or decreasingbend radii by combining inflation of overlapping subsets of theballoons. Note also that a single lumen may be used for both inflationand deflation of the balloons, and that multi-lumen structures of morethan 6 lumens may be provided, so that still further combinations thesedegrees of freedom may be employed.

In the embodiment illustrated in the side view of FIG. 9 and in thecross-section of FIG. 10, the outer diameter of the helical coils isabout 0.130 inches. Multi-lumen structures 440 a, 440 b have outerdiameters in a range from about 0.020 inches to about 0.030 inches(optionally being about 0.027 inches), with the lumens having innerdiameters of about 0.004 inches and the walls around each lumen having aminimum thickness of 0.004 inches. Despite the use of inflationpressures of 20 atm or more, the small diameters of the lumens helplimit the strain on the helical core structures, which typicallycomprise polymer, ideally being extruded. Rather than including aresilient wire or the like in the multi-lumen structure, axialcompression of the balloons (and straightening of the catheter axisafter deflation) is provided primarily by use of a metal in coils 442 a,442 b. Opposed concave axial surfaces of coils 442 help maintain radialpositioning of the balloons and multi-lumen structures between thecoils. Affixing the ends of resilient coils 442 and balloonsupply/support structures 440 together to the inner and outer sheaths atthe ends of the coils, and optionally between segments may help maintainthe helical shapes as well. Increasing the axial thickness of coils 442and the depth of the concave surfaces may also be beneficial to helpmaintain alignment, with the coils then optionally comprising polymerstructures. Still other helical-maintaining structures may be includedin most or all of the helical embodiments described herein, includingperiodic structures that are affixed to coils 442 or other helicalskeleton members, the periodic structures having protrusions that extendbetween balloons and can engage the ends of the inflated balloon wallsto maintain or index lateral balloon orientations.

Many of the embodiments described herein provide fluid-drivenarticulation of catheters, guidewires, and other elongate flexiblebodies. Advantageously, such fluid driven articulation can rely on verysimple (and small cross-section) fluid transmission along the elongatebody, with most of the forces being applied to the working end of theelongate body reacting locally against the surrounding environmentrather than being transmitted back to a proximal handle or the like.This may provide a significant increase in accuracy of articulation,decrease in hysteresis, as well as a simpler and lower cost articulationsystem, particularly when a large number of degrees of freedom are to beincluded. Note that the presence of relatively high pressure fluid,and/or low temperature fluid, and/or electrical circuitry adjacent thedistal end of an elongate flexible body may also be used to enhance thefunctionality of tools carried by the body, particularly by improving oradding diagnostic tools, therapeutic tools, imaging or navigationstools, or the like.

Referring now to FIG. 12, a radially elongate polymer helical ballooncore structure 450 generally has a cross section with a radial thickness452 that is significantly greater than its axial thickness 454. Radialthickness 452 may optionally be, for example 80% or more of the inflateddiameter of the surrounding balloon, while axial thickness 454 may bebetween 20% and 75% of the inflated diameter. As compared to a circularcore cross-section, such an elongate cross-section provides additionalterritory for balloon lumens extending within the coil core (allowingmore lumens and separately inflatable balloons or groups of balloons,and/or allowing larger lumen sizes for faster actuation times) with thesame the axial actuation stroke of the surrounding balloon. Theexemplary cross-sectional shapes include elliptical or othercontinuously curved shapes to facilitate sealing engagement with thesurrounding balloon wall material, with an alternative having proximaland distal regions with circular curvatures corresponding to those ofthe inflated balloon (so as to enhance axially compressive forcetransmission against an axially indented coil spring surface configuredto evenly engage the inflated balloon).

Referring now to FIGS. 17A and 17B, articulation system componentsrelated to those of FIGS. 9-11 can be seen. Two multi-lumen polymerhelical cores 440 can be interleaved with axially concave helicalsprings along the articulated portion of a catheter. Curved transitionzones extend proximal of the helical cores to axially straightmulti-lumen extensions 540, which may extend along a passive(unarticulated) section of the catheter, or which may extend througharticulated segments that are driven by fluid transmitted by otherstructures (not shown).

Extensions 540 extend proximally into a valve assembly 542 so as toprovide fluid communication between fluid pathways of the valve assemblyand the balloons of the articulated segment. Valve assembly 542 includesan axial series of modular valve units 542 a, 542 b, 542 c, etc.Endplates and bolts seal fluid paths within the valve assembly and holdthe units in place. Each valve assembly 542 includes at least one fluidcontrol valve 544, and preferably two or more valves. The valves maycomprise pressure modulating valves that sense and control pressure,gate valves, three-way valves (to allow inflation fluid along a channelto one or more associated balloons, to seal inflation fluid in theinflation channel and associated balloons while flow from the fluidsource is blocked, and to allow inflation fluid from the channels andballoons to be released. O-rings provide sealing between the valves andaround the extensions 540, and unthreading the bolts may releasepressure on the o-rings and allow the extensions to be pulled distallyfrom the valve assembly, thereby providing a simple quick-disconnectcapability. Radial ports 546 are axially spaced along extensions 540 toprovide fluid communication between the valves and associated lumens ofthe multi-lumen polymer extensions, transitions, and helical coils.Advantageously, where a greater or lesser number of inflation channelswill be employed, more or fewer valve units may be axially stackedtogether. While valves 544 are here illustrated with external fluidtubing connectors (to be coupled to the fluid source or the like), thefluid paths to the valves may alternatively also be included within themodular valve units, for example, with the fluid supply beingtransmitted to each of the valves along a header lumen that extendsaxially along the assembly and that is sealed between the valve unitsusing additional o-rings or the like.

Many of the flexible articulated devices described above rely oninflation of one or more balloons to articulate a structure from a firstresting state to a second state in which a skeleton of the flexiblestructure is resiliently stressed. By deflating the balloons, theskeleton can urge the flexible structure back toward the originalresting state. This simple system may have advantages for manyapplications. Nonetheless, there may be advantages to alternativesystems in which a first actuator or set of actuators urges a flexiblestructure from a first state (for example, a straight configuration) toa second state (for example, a bent or elongate configuration), and inwhich a second actuator or set of actuators are mounted in opposition tothe first set such that the second can actively and controllably urgethe flexible structure from the second state back to the first state.Toward that end, exemplary systems described below often use a first setof balloons to locally axially elongate a structural skeleton, and asecond set of balloons mounted to the skeleton to locally axiallycontract the structural skeleton. Note that the skeletons of suchopposed balloon systems may have very little lateral or axial stiffness(within their range of motion) when no balloons are inflated.

Referring now to FIGS. 13 and 14, a simplified exemplary C-channelstructural skeleton 630 (or portion or cross section of a skeleton) isshown in an axially extended configuration (in FIG. 13), and in anaxially contracted configuration (in FIG. 14). C-frame skeleton 630includes an axial series of C-channel members or frames 632 extendingbetween a proximal end 634 and a distal end 636, with each rigidC-channel including an axial wall 638, a proximal flange 640, and adistal flange 642 (generically referenced as flanges 640). The opposedmajor surfaces of the walls 644, 646 are oriented laterally, and theopposed major surfaces of the flanges 648, 650 are oriented axially (andmore specifically distally and proximally, respectively. The C-channelsalternate in orientation so that the frames are interlocked by theflanges. Hence, axially adjacent frames overlap, with the proximal anddistal surfaces 650, 648 of two adjacent frames defining an overlapoffset 652. The flanges also define additional offsets 654, with theseoffsets being measured between flanges of adjacent similarly orientedframes.

In the schematics of FIGS. 13 and 14, three balloons are disposed in thechannels of each C-frame 632. Although the balloons themselves may (ormay not) be structurally similar, the balloons are of two differentfunctional types: extension balloons 660 and contraction balloons 662.Both types of balloons are disposed axially between a proximallyoriented surface of a flange that is just distal of the balloon, and adistally oriented surface of a flange that is just proximal of theballoon. However, contraction balloons 662 are also sandwiched laterallybetween a first wall 638 of a first adjacent C-channel 632 and a secondwall of a second adjacent channel. In contrast, extension balloons 660have only a single wall on one lateral side; the opposite sides ofextension balloons 660 are not covered by the frame (though they willtypically be disposed within a flexible sheath or other components ofthe overall catheter system).

A comparison of C-frame skeleton 630 in the elongate configuration ofFIG. 13 to the skeleton in the short configuration of FIG. 14illustrates how selective inflation and deflation of the balloons can beused to induce axial extension and contraction. Note that the C-frames632 are shown laterally reversed from each other in these schematics. InFIG. 13, extension balloons 660 are being fully inflated, pushing theadjacent flange surfaces apart so as to increase the axial separationbetween the associated frames. As two contraction balloons 662 aredisposed in each C-channel with a single extension balloon, and as thesize of the channel will not significantly increase, the contractionballoons will often be allowed to deflate at least somewhat withexpansion of the extension balloons. Hence, offsets 654 will be urged toexpand, and contraction offsets 652 will be allowed to decrease. Incontrast, when skeleton 630 is to be driven toward the axiallycontracted configuration of FIG. 14, the contraction balloons 662 areinflated, thereby pushing the flanges of the overlapping frames axiallyapart to force contraction overlap 652 to increase and axially pull thelocal skeleton structure into a shorter configuration. To allow the twocontraction balloons 662 to expand within a particular C-channel, theexpansion balloons 660 can be allowed to deflate.

While the overall difference between C-frame skeleton 630 in thecontracted configuration and in the extended configuration issignificant (and such skeletons may find advantagous uses), it isworthwhile noting that the presence of one extension balloon and twocontraction balloons in a single C-channel may present disadvantages ascompared to other extension/contraction frame arrangements describedherein. In particular, the use of three balloons in one channel canlimit the total stroke or axial change in the associated offset thatsome of the balloons may be able to impose. Even if similar balloon/coreassemblies are used as extension and contraction balloons in athree-balloon wide C-channel, the two contraction balloons may only beused for about half of the stroke of the single extension balloon, asthe single extension stroke in the channel may not accommodate two fullcontractions strokes. Moreover, there are advantages to limiting thenumber of balloon/core assemblies used in a single articulated segment.

Note that whichever extension/contraction skeleton configuration isselected, the axial change in length of the skeleton that is inducedwhen a particular subset of balloons are inflated and deflated willoften be local, optionally both axially local (for example, so as tochange a length along a desired articulated segment without changinglengths of other axial segments) and—where the frames extend laterallyand/or circumferentially—laterally local (for example, so as to impose alateral bend by extending one lateral side of the skeleton withoutchanging an axial length of the other lateral side of the skeleton).Note also that use of the balloons in opposition will often involvecoordinated inflating and deflating of opposed balloons to provide amaximum change in length of the skeleton. There are significantadvantages to this arrangement, however, in that the ability toindependently control the pressure on the balloons positioned on eitherside of a flange (so as to constrain an axial position of that flange)allows the shape and the position or pose of the skeleton to bemodulated. If both balloons are inflated evenly at with relatively lowpressures (for example, at less that 10% of full inflation pressures),the flange may be urged to a middle position between the balloons, butcan move resiliently with light environmental forces by compressing thegas in the balloons, mimicking a low-spring force system. If bothballoons are evenly inflated but with higher pressures, the skeleton mayhave the same nominal or resting pose, but may then resist deformationfrom that nominal pose with a greater stiffness.

An alternative S-channel skeleton 670 is shown schematically incontracted and extended configurations in FIGS. 15 and 16, respectively,which may have both an improved stroke efficiency (giving a greaterpercent change in axial skeleton length for an available balloon stroke)and have fewer components than skeleton 632. S-skeleton 670 has many ofthe components and interactions described above regarding C-frameskeleton 630, but is here formed of structural S-channel members orframes 672. Each S-channel frame 672 has two walls 644 and three flanges640, the proximal wall of the frame having a distal flange that isintegral with the proximal flange of the distal wall of that frame.Axially adjacent S-channels are again interlocked, and in thisembodiment, each side of the S-channel frame has a channel that receivesone extension balloon 660 and one contraction balloon 662. This allowsall extension balloons and all contraction balloons to take fulladvantage of a common stroke. Moreover, while there are two extensionballoons for each contraction balloon, every other extension balloon mayoptionally be omitted without altering the basic extension/contractionfunctionality (though the forces available for extension may bereduced). In other words, if the extension balloons 660′ as marked withan X were omitted, the skeleton could remain fully constrainedthroughout the same nominal range of motion. Hence, S-channel frame 672may optionally use three or just two sets of opposed balloons for aparticular articulation segment.

Referring now to FIG. 17, a modified C-frame skeleton 680 has componentsthat share aspects of both C-frame skeleton 630 and S-frame skeleton670, and may offer advantages over both in at least some embodiments.Modified C skeleton 680 has two different generally C-frames or members:a C-frame 682, and a bumper C-frame 684. C-frame 682 and bumper frame 64both have channels defined by walls 644 and flanges 648 with an axialwidth to accommodate two balloon assemblies, similar to the channels ofthe S-frames 672. Bumper frame 684 also has a protrusion or nub 686 thatextends from one flange axially into the channel. The adjacent axialsurfaces of these different frame shapes engage each other at the nub686, allowing the frames to pivot relative to each other andfacilitating axial bending of the overall skeleton, particularly whenusing helical frame members.

Referring now to FIGS. 18 and 19, a relationship between the schematicextension/retraction frame illustration of FIGS. 13-17 and a firstexemplary three dimensional skeleton geometry can be understood. To forman axisymmetric ring-frame skeleton structure 690 from the schematicmodified C-frame skeleton 680 of FIG. 18, the geometry of frame members682, 684 can be rotated about an axis 688, resulting in annular or ringframes 692, 694. These ring frames retain the wall and flange geometrydescribed above, but now with annular wall and flanges beinginterlocked. The annular C-frames 682, 684 were facing differentdirections in schematic skeleton 680, so that outer C-frame ring 692 hasan outer wall (sometimes being referred to as outer ring frame 692) anda channel that opens radially inwardly, while bumper C-frame ring 694has a channel that is open radially outwardly and an inner wall (so thatthis frame is sometimes referred to as the inner ring frame 694). Ringnub 696 remains on inner ring frame 694, but could alternatively beformed on the adjacent surface of the outer ring frame (or usingcorresponding features on both). Note that nub 696 may add more valuewhere the frame deforms with bending (for example, the frame deformationwith articulation of the helical frame structures described below) asthe deformation may involve twisting that causes differential angels ofthe adjacent flange faces. Hence, a non-deforming ring frame structuremight optionally omit the nub in some implementations.

Referring now to FIGS. 19-22, uniform axial extension and contraction ofa segment of ring-frame skeleton 690 is performed largely as describedabove. To push uniformly about the axis of the ring frames, threeballoons are distributed evenly about the axis between the flanges (withcenters separated by 120 degrees). The balloons are shown here asspheres for simplicity, and are again separated into extension balloons660 and contraction balloons 662. In the straight extended configurationof FIG. 20, the extension balloons 660 of the segment are all fullyinflated, while the contraction balloons 662 are all fully deflated. Inan intermediate length configuration shown in FIG. 21, both sets ofballoons 660, 662 are in an intermediate inflation configuration. In theshort configuration of FIG. 22, contraction balloons 662 are all fullyinflated, while extension balloons 660 are deflated. Note that the stateof the balloons remains axisymmetrical, so that the lengths on alllateral sides of the ring frame skeleton 690 remain consistent and theaxis of the skeleton remains straight.

As can be understood with reference to FIGS. 22A and 22B, lateralbending or deflection of the axis of ring-frame skeleton 690 can beaccomplished by differential lateral inflation of subsets of theextension and contraction balloons. There are three balloons distributedabout the axis between each pair of articulated flanges, so that theextension balloons 660 are divided into three sets 660 i, 660 ii, and660 iii. Similarly, there are three sets of contraction balloons 662 i,662 ii, and 662 iii. The balloons of each set are aligned along the samelateral orientation from the axis. In some exemplary embodiments, eachset of extension balloons (extension balloons 660 i, extension balloons660 ii, and extension balloons 660 iii) along a particular segment iscoupled to an associated inflation fluid channel (for example, a channeli for extension balloons 660 i, a channel ii for extension balloons 660ii, and a channel iii for extension balloons 660 iii, the channels notshown here). Similarly, each set of contraction balloons 662 i, 662 ii,and 662 iii is coupled to an associated inflation channel (for example,channels iv, v, and vi, respectively) so that there are a total of 6lumens or channels per segment (providing three degrees of freedom andthree orientation-related stiffnesses). Other segments may have separatefluid channels to provide separate degrees of freedom, and alternativesegments may have fewer than 6 fluid channels. Regardless, byselectively deflating the extension balloons of a first lateralorientation 660 i and inflating the opposed contraction balloons 662 i,a first side of ring frame skeleton 690 can be shortened. By selectivelyinflating the extension balloons of the other orientations 660 ii, 660iii, and by selectively deflating the contraction balloons of thoseother orientations 662 ii, 662 iii, the laterally opposed portion ofring frame skeleton 690 can be locally extended, causing the axis of theskeleton to bend. By modulating the amount of elongation and contractiondistributed about the three opposed extension/contraction balloonorientations, the skeleton pose can be smoothly and continuously movedand controlled in three degrees of freedom.

Referring now to FIGS. 23A and 23B, as described above with reference toFIGS. 15 and 16, while it is possible to include balloons between allthe separated flanges so as to maximize available extension forces andthe like, there may be advantages to foregoing kinematically redundantballoons in the system for compactness, simplicity, and cost. Towardthat end, ring frame skeletons having 1-for-1 opposed extension andcontraction balloons (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and662 iii) can provide the same degrees of freedom and range of motion asprovided by the segments of FIGS. 22A and 22B (including two transverseX-Y lateral bending degrees of freedom and an axial Z degree offreedom), and can also control stiffness, optionally differentiallymodulating stiffness of the skeleton in different orientations in 3Dspace. The total degrees of freedom of such a segment may appropriatelybe referenced as being 4-D (X,Y,Z,&S for Stiffness), with the stiffnessdegree of freedom optionally having 3 orientational components (so as toprovide as many as 5-D or 6-D. Regardless, the 6 fluid channels may beused to control 4 degrees of freedom of the segment.

As can be understood with reference to FIGS. 23C-23E and 23H, elongateflexible bodies having ring-frame skeletons 690′ with larger numbers ofinner and outer ring frames 692, 694 (along with associated largernumbers of extension and retraction balloons) will often provide agreater range of motion than those having fewer ring frames. Theelongation or Z axis range of motion that can be provided by balloonarticulation array may be expressed as a percentage of the overalllength of the structure, with larger percentage elongations providinggreater ranges of motion. The local changes in axial length that aballoon array may be able to produce along a segment having ring frames690, 690′ (or more generally having the extension contraction skeletonsystems described herein) may be in a range of from about 1 percent toabout 45 percent, typically being from about 2½ percent to about 25percent, more typically being from about 5 percent to about 20 percent,and in many cases being from about 7½ percent to about 17½ percent ofthe overall length of the skeleton. Hence, the longer axial segmentlength of ring frame skeleton 690′ will provide a greater axial range ofmotion between a contracted configuration (as shown in FIG. 23E) and anextended configuration (as shown in FIG. 23C), while still allowingcontrol throughout a range of intermediate axial length states (as shownin FIG. 23D).

As can be understood with reference to FIGS. 23A, 23B, 23D and 23H,setting the balloon pressures so as to axially contract one side of aring frame skeleton 690′ (having a relatively larger number of ringframes) and axially extend the other side laterally bends or deflectsthe axis of the skeleton through a considerable angle (as compared to aring frame skeleton having fewer ring frames), with each frame/frameinterface typically between 1 and 15 degrees of axial bend angle, moretypically being from about 2 to about 12 degrees, and often being fromabout 3 to about 8 degrees. A catheter or other articulated elongateflexible body having a ring frame skeleton may be bent with a radius ofcurvature (as measured at the axis of the body) of between 2 and 20times an outer diameter of the skeleton, more typically being from about2.25 to about 15 times, and most often being from about 2.4 to about 8times. While more extension and contraction balloons 660, 662 are usedto provide this range of motion, the extension and contraction balloonsubsets (660 i, 660 ii, and 660 iii; and 662 i, 662 ii, and 662 iii) maystill each be supplied by a single common fluid supply lumen. Forexample 6 fluid supply channels may each be used to inflate and deflate16 balloons in the embodiment shown, with the balloons on a single lumenbeing extension balloons 660 i aligned along one lateral orientation.

As can be understood with reference to ring frame skeleton 690′ in thestraight configuration of FIG. 23D, in the continuously bentconfiguration of FIG. 23H, and in the combined straight and bentconfiguration of FIG. 23F, exemplary embodiments of the elongateskeleton 690′ and actuation array balloon structures described hereinmay be functionally separated into a plurality of axial segments 690 i,690 ii. Note that many or most of the skeleton components (includingframe members or axial series of frame members, and the like) andactuation array components (including the substrate and/or core, some orall of the fluid channels, the balloon outer tube or sheath material,and the like), along with many of the other structures of the elongateflexible body (such as the inner and outer sheaths, electricalconductors and/or optical conduits for diagnostic, therapeutic, sensing,navigation, valve control, and other functions) may extend continuouslyalong two or more axial segments with few or no differences betweenadjacent segments, and optionally without any separation in thefunctional capabilities between adjacent segments. For example, anarticulated body having a two-segment ring frame skeleton 690′ system asshown in FIG. 23H may have a continuous axial series of inner and outerring frames 692, 694 that extends across the interface between thejoints such that the two segments can be bent in coordination with aconstant bend radius by directing similar inflation fluid quantities andpressures along the fluid supply channels associated with the twoseparate segments. As can be understood with reference to FIG. 23G,other than differing articulation states of the segments, there mayoptionally be few or no visible indications of where one segment endsand another begins.

Despite having many shared components (and a very simple and relativelycontinuous overall structure), functionally separating an elongateskeleton into segments provides tremendous flexibility and adaptabilityto the overall articulation system. Similar bend radii may optionally beprovided with differing stiffnesses by applying appropriately differingpressures to the opposed balloons 660, 662 of two (or more) segments 690i, 690 ii. Moreover, as can be understood with reference to FIG. 23F,two (or more) different desired bend radii, and/or two different lateralbend orientations and/or two different axial segments lengths can beprovided by applying differing inflation fluid supply pressures to theopposed contraction/extension balloon sets 660 i, 660 ii, 660 iii, 662i, 662 ii, 662 iii of the segments. Note that the work spaces ofsingle-segment and two-segment systems may overlap so that both types ofsystems may be able to place an end effector or tool at a desiredposition in 3D space (or even throughout a desired range of locations),but multiple-segment systems will often be able to achieve additionaldegrees of freedom, such as allowing the end effector or tool to beoriented in one or more rotational degrees of freedom in 6D space. Asshown in FIG. 23J, articulated systems having more than two segmentsoffer still more flexibility, with this embodiment of ring frameskeleton 690′ having 4 functional segments 690 a, 690 b, 690 c, and 690d. Note that still further design alternatives may be used to increasefunctionality and cost/complexity of the system for a desired workspace,such as having segments of differing length (such as providing arelatively short distal segment 690 a supported by a longer segmenthaving the combined lengths of 690 b, 690 c, and 690 d. While many ofthe multi-segment embodiments have been shown and described withreference to to planar configurations of the segments where all thesegments lie in a single plane and are either straight or in a fullybent configuration, it should also be fully understood that theplurality of segments 690 i, 690 ii, etc., may bend along differingplanes and with differing bend radii, differing axial elongation states,and/or differing stiffness states, as can be understood with referenceto FIG. 23I.

Catheters and other elongate flexible articulated structures having ringframe skeletons as described above with reference to FIGS. 19-23Iprovide tremendous advantages in flexibility and simplicity over knownarticulation systems, particularly for providing large numbers ofdegrees of freedom and when coupled with any of the fluid supply systemsdescribed herein. Suitable ring frames may be formed of polymers (suchas nylons, urethanes, PEBAX, PEEK, HDPE, UHDPE, or the like) or metals(such as aluminum, stainless steel, brass, silver, alloys, or the like),optionally using 3D printing, injection molding, laser welding, adhesivebonding, or the like. Articulation balloon substrate structures mayinitially be fabricated and the balloon arrays assembled with thesubstrates in a planar configuration as described above, with the arraysthen being assembled with and/or mounted on the skeletons, optionallywith the substrates being adhesively bonded to the radially innersurfaces of the inner rings and/or to the radially outer surfaces of theouter rings, and with helical or serpentine axial sections of thesubstrate bridging between ring frames. While extension and retractionballoons 660, 662 associated with the ring frame embodiments are shownas spherical herein, using circumferentially elongate (and optionallybent) balloons may increase an area of the balloon/skeleton interface,and thereby enhance axial contraction and extension forces. A hugevariety of modifications might also be made to the general ring-frameskeletal arrangement and the associated balloon arrays. For example,rather than circumferentially separating the balloons into three lateralorientations, alternative embodiments may have four lateral orientations(+X, −X, +Y, and −Y) so that four sets of contraction balloons aremounted to the frame in opposition to four sets of extension balloons.Regardless, while ring-frame skeletons have lots of capability andflexibility and are relatively geometrically simple so that theirfunctionality is relatively easy to understand, alternativeextension/contraction articulation systems having helical skeletonmembers (as described below) may be more easily fabricated and/or moreeasily assembled with articulation balloon array components,particularly when using the advantageous helical multi-lumen coresubstrates and continuous balloon tube structures described above.

First reviewing components of an exemplary helical framecontraction/expansion articulation system, FIGS. 24A-24E illustrateactuation balloon array components and their use in a helical balloonassembly. FIGS. 24F and 24G illustrate exemplary outer and inner helicalframe members. After reviewing these components, the structure and useof exemplary helical contraction/expansion articulation systems(sometimes referred to herein as helical push/pull systems) can beunderstood with reference to FIGS. 25 and 26.

Referring now to FIGS. 24A and 24B, an exemplary multi-lumen conduit orballoon assembly core shaft has a structure similar to that of the coredescribed above with reference to FIGS. 14 and 15. Core 702 has aproximal end 704 and a distal end 706 with a multi-lumen body 708extending therebetween. A plurality of lumens 710 a, 710 b, 710 c, . . .extend between the proximal and distal ends. The number of lumensincluded in a single core 702 may vary between 3 and 30, with exemplaryembodiments have 3, 7 (of which one is a central lumen), 10 (including 1central), 13 (including 1 central), 17 (one being central), or the like.The multi-lumen core will often be round but may alternatively have anelliptical or other elongate cross-section as described above. Whenround, core 702 may have a diameter 712 in a range from about 0.010″ toabout 1″, more typically being in a range from about 0.020″ to about0.250″, and ideally being in a range from about 0.025″ to about 0.100″for use in catheters. Each lumen will typically have a diameter 714 in arange from about 0.0005″ to about 0.05″, more preferably having adiameter in a range from about 0.001″ to about 0.020″, and ideallyhaving a diameter in a range from about 0.0015″ to about 0.010″. Thecore shafts will typically comprise extruded polymer such as a nylon,urethane, PEBAX, PEEK, PET, other polymers identified above, or thelike, and the extrusion will often provide a wall thickness surroundingeach lumen of more than about 0.0015″, often being about 0.003″ or more.The exemplary extruded core shown has an OD of about 0.0276″″, and 7lumens of about 0.004” each, with each lumen surrounded by at least0.004″ of the extruded nylon core material.

Referring still to FIGS. 24A and 24B, the lumens of core 702 may haveradial balloon/lumen ports 716 a, 716 b, 716 c, . . . , with each portcomprising one or more holes formed through the wall of core 702 andinto an associated lumen 710 a, 710 b, 710 c, . . . respectively. Theports are here shown as a group of 5 holes, but may be formed using 1 ormore holes, with the holes typically being round but optionally beingaxially elongate and/or shaped so as to reduce pressure drop of fluidflow therethrough. In other embodiments (and particularly those having aplurality of balloons supplied with inflation fluid by a single lumen),having a significant pressure drop between the lumen and the balloon mayhelp even the inflation state of balloons, so that a total cross sectionof each port may optionally be smaller than a cross-section of the lumen(and/or by limiting the ports to one or two round lumens). Typical portsmay be formed using 1 to 10 holes having diameters that are between 10%of a diameter of the associated lumen and 150% of the diameter of thelumen, often being from 25% to 100%, and in many cases having diametersof between 0.001″ and 0.050″. Where more than one hole is included in aport they will generally be grouped together within a span that isshorter than a length of the balloons, as each port will be containedwithin an associated balloon. Spacing between the ports will correspondto a spacing between balloons to facilitate sealing of each balloon fromthe axially adjacent balloons.

Regarding which lumens open to which ports, the ports along a distalportion of the core shaft will often be formed in sets, with each setbeing configured to provide fluid flow to and from an associated set ofballoons that will be distributed along the loops of the core (once thecore is bent to a helical configuration) for a particular articulatedsegment of the articulated flexible body. When the number of lumens inthe core is sufficient, there will often be separate sets of ports fordifferent segments of the articulated device. The ports of each set willoften form a periodic pattern along the axis of the multi-lumen core702, so that the ports provide fluid communication into M differentlumens (M being the number of different balloon orientations that are tobe distributed about the articulated device axis, often being 3 or 4,i.e., lumen 710 a, lumen 710 b, and lumen 710 c) and the patternrepeating N times (N often being the number of contraction balloonsalong each orientation of a segment). Hence, the multi-lumen coreconduit can function as a substrate that supports the balloons, and thatdefines the balloon array locations and associated fluid supply networksdescribed above. Separate multi-lumen cores 702 and associated balloonarrays may be provided for contraction and expansion balloons.

As one example, a port pattern might be desired that includes a 3×5contraction balloon array for a particular segment of a catheter. Thisset of ports might be suitable when the segment is to have three lateralballoon orientations (M=3) and 5 contraction balloons aligned along eachlateral orientation (N=5). In this example, the distal-most port 716 aof the set may be formed through the outer surface of the core into afirst lumen 710 a, the next proximal port 716 b to lumen 710 b, the nextport 716 c to lumen 710 c, so that the first 3 (M) balloons define an“a, b, c” pattern that will open into the three balloons that willeventually be on the distal-most helical loop of the set. The samepattern may be repeated 5 times (for example: a, b, c, a, b, c, a, b, c,a, b, c, a, b, c) for the 5 loops of the helical coil that will supportall 15 contraction balloons of a segment to the fluid supply system suchthat the 5 contraction balloons along each orientation of the segmentare in fluid communication with a common supply lumen. Where the segmentwill include expansion balloons mounted 1-to-1 in opposition to thecontraction balloons, a separate multi-lumen core and associated balloonmay have a similar port set; where the segment will include 2 expansionballoons mounted in opposition for each contraction balloon, twoseparate multi-lumen cores and may be provided, each having a similarport set.

If the same multi-lumen core supplies fluid to (and supports balloonsof) another independent segment, another set of ports may be providedaxially adjacent to the first pattern, with the ports of the second setbeing formed into an M′×N′ pattern that open into different lumens ofthe helical coil (for example, where M′=3 and N′=5: d, e, f, d, e, f, d,e, f, d, e, f, d, e, f), and so on for any additional segments. Notethat the number of circumferential balloon orientations (M) will oftenbe the same for different segments using a single core, but may bedifferent in some cases. When M differs between different segments ofthe same core, the spacing between ports (and associated balloonsmounted to the core) may also change. The number of axially alignedcontraction balloons may also be different for different segments of thesame helical core, but will often be the same. Note also that all theballoons (and associated fluid lumens) for a particular segment that areon a particular multi-lumen core will typically be either only extensionor only contraction balloons (as the extension and contraction balloonarrays are disposed in helical spaces that may be at least partiallyseparated by the preferred helical frame structures described below). Asingle, simple pattern of ports may be disposed near the proximal end ofcore shaft 702 to interface each lumen with an associated valve plate ofthe manifold, the ports here being sized to minimized pressure drop andthe port-port spacing corresponding to the valve plate thickness.Regardless, the exemplary core shown has distal ports formed usinggroups of 5 holes (each having a diameter of 0.006″, centerline spacingwithin the group being 0.012″), with the groups being separated axiallyby about 0.103″.

Referring now to FIGS. 24C and 24D, a continuous tube of flexibleballoon wall material 718 may be formed by periodically varying adiameter of tube wall material to form a series of balloon shapes 720separated by smaller profile sealing zones 722. Balloon tube 718 mayinclude between about 9 and about 290 regularly spaced balloon shapes720, with the sealing zones typically having an inner diameter that isabout equal to the outer diameters of the multi-lumen helical coreshafts 702 described above. In some embodiments, the inner diameters ofthe sealing zones may be significantly larger than the outer diametersof the associated cores when the balloon tube is formed, and thediameters of the sealing zones may be decreased (such as by heatshrinking or axially pull-forming) before or during assembly of theballoon tube and core shaft. The sealing zone may have a length ofbetween about 0.025″ and about 0.500″, often being between about 0.050″and about 0.250″. Decreasing the length of the sealing zone allows thelength of the balloon to be increased for a given catheter size so as toprovide larger balloon/frame engagement interfaces (and thus greaterarticulation forces), while longer sealing zones may facilitate assemblyand sealing between balloons so as to avoid cross-talk betweenarticulation channels.

Referring still to FIGS. 24C and 24D, the balloon shapes 720 of theballoon tube 718 may have diameters that are larger than the diametersof the sealing zones by between about 10% and about 200%, more typicallybeing larger by an amount in a range from about 20% to about 120%, andoften being from about 40% to about 75%. The thickness of balloon tube718 will often vary axially with the varying local diameter of the tube,the locally large diameter portions forming the balloon shapesoptionally being in a range from about 0.00008′ (or about 2 microns) toabout 0.005″, typically being from about 0.001″ and about 0.003″.Balloon tube 718 may initially be formed with a constant diameter andthickness, and the diameter may be locally expanded (by blow forming, byvacuum forming, by a combination of both blow forming and vacuumforming, or by otherwise processing the tube material along the balloonshapes 720), and/or the diameter of the balloon tube may be locallydecreased (by heat shrinking, by axial pull-forming, by a combination ofboth heat shrinking and pull forming, or by otherwise processing thetube material along the sealing zones), with the tube material oftenbeing processed so as to both locally expand the diameter along thedesired balloon shapes and to locally contract the diameter along thesealing zones. Particularly advantageous techniques for forming balloontubes may include the use of extruded polymer tubing corrugators,including the vertical small bore corrugators commercially availablefrom Unicore, Corma, Fraenkische, and others. Suitable custom molds forsuch pipe corrugators may be commercially available from GlobalMed,Custom Pipe, Fraenkische, and others. Still more advanced fabricationtechniques may allow blow or vacuum corrugation using a robotic shuttlecorrugator and custom molds, particularly when it is desirable to changea size or spacing of balloons along a continuous tube. It should benoted that while a single continuous balloon tube is shown, a pluralityof balloon tubes (each having a plurality (or in some cases, at leastone) balloon shape) can be sealingly mounted onto a single core.Regardless, the sealing zones will often have a material thickness thatis greater than that of the balloon shapes.

The balloon shapes 720 of the balloon tube 718 may each have arelatively simple cylindrical center section prior to assembly as shown.The tapers between the balloon center sections and the sealing zones cantake any of a variety of shapes. The tapers may, for example, be roughlyconical, rounded, or squared, and will preferably be relatively short soas to allow greater balloon/frame engagement for a given landing zonelength. More complex embodiments may also be provided, including formingthe balloon shapes with curved cylindrical center sections, optionallywhile corrugating or undulating the surfaces of the tapers so that theballoon tube overall remains relatively straight. The lengths of eachcenter section is typically sufficient to define an arc-angle of from 5to 180 degrees about the axis of the desired balloon assembly helix,more typically being from about 10 to about 50 degrees, the lengths ofthe center sections often being in a range from about 0.010″ to about0.400″ for medical applications, more typically being from about 0.020″to about 0.150″, and many times being in a range from about 0.025″ toabout 0.100″. The exemplary balloon shapes may have an outer diameter ofabout 0.051″ over a total balloon length (including the tapers) of about0.059″

As can be understood with reference to FIGS. 24C, 24D, 24E, and theaxial view of FIG. 24E1, balloon tube 718 may be sealingly affixed tocore 702, and the core/balloon tube assembly may then be formed into adesired helical shape. The balloon tube may be sealed over the helicalcore using adhesive (such as any of those described above, oftenincluding UV-cured adhesives) thermal bonding, laser bonding, diebonding, and/or the like. Sealing of the balloons may also benefit froma compression structure disposed over the balloon material to helpmaintain tube/core engagement when the balloons are inflated. Suitablecompression structures or techniques may include short sections ofheat-shrink materials (such as PET) shrunk onto the sealing zones,high-strength filament windings wrapped circumferentially around thesealing zones and adhesively bonded, swaging of metallic ring structuressimilar to marker bands over the sealing zones, small bore crimp clampsover the sealing zones, heat-shrinking and/or pull forming the balloontube onto the core, or the like. Any two or more of these may also becombined, for example, with the balloon tube being adhesively bonded tothe core tube by injecting adhesive into the balloon tube around thesealing zone, heat shrinking the balloon tube and a surrounding PETsleeve over the sealing zone, and then swaging a metallic marker bandover the sealing PET sleeve (so that the sleeve provides strain relief).Regardless, ports 716 will preferably be disposed within correspondingballoon shapes 720 and will remain open after the balloon/core assembly730 is sealed together in the straight configuration shown in FIG. 24D.Shape setting of the balloon/core assembly from the straightconfiguration to the helically curved configuration of FIG. 24E can beperformed by wrapping the assembly around and/or within a mandrel andheating the wrapped assembly. Helical channels may be included in themandrel, which may also have discrete balloon receptacles or features tohelp ensure alignment of sets of balloons along the desired lateralballoon axes. Regardless, shape setting of the core/balloon assembly canhelp set the M different lateral orientations of the balloons, so thatthe balloons of each set 720 i, 720 ii, 720 iii are aligned.

Referring to FIG. 24E-2, an alternative balloon tube 718′ has aplurality of pre-curved balloon shapes 720′ coupled together by sealingzones 722 to facilitate forming and/or keeping the balloon/core assemblyin a helical configuration. The overall configuration of alternativeballoon tube 718′ is straight, and it may be beneficial to provideasymmetric corrugated transitions 725 between pre-curved balloon shapes720′ and sealing zones 722. Corrugated transitions 725 may have a formanalogous to that of a corrugated straw along at least an outer radialportion of the helix, and the balloon shapes may optionally havecorrugations along this outer portion instead of or in addition to thepre-curvature shown schematically here. The balloon shapes, transitions,and sealing zones may be formed by blow molding within machined orprinted tooling using medical balloon blowing techniques, by blowmolding with the moving tooling of a corrugation system, or the like.

Referring now to FIGS. 24F and 24G, exemplary inner and outer helicalC-channel frames, 732 and 734 respectively, can be seen. Inner helicalframe 732 and outer helical frame 734 incorporate the modified C-channelframe 680 of FIG. 17, but with the C-channels defined by axiallycontinuous helical walls 736 with flanges 740 along their proximal anddistal helical edges. The helical flanges are axially engaged by opposedballoons and allow inflation of the balloons to locally axially contractand/or extend the skeleton and catheter (or other articulatable body) ina manner that is analogous to the annular flanges of the ring framesdescribed above. An optional helical nub 742 protrudes axially into thechannel of inner ring frame 734 to allow the frames to pivot againsteach other along a flange/flange engagement, so that the nub couldinstead be included on the flange of the outer frame or on both (or maycomprise a separate structure that is axially sandwiched between theflanges of the two frames). Alternative embodiments may forego such apivotal structure altogether.

Referring now to FIGS. 25A-25D, a segment of an exemplary flexibleextension/contraction helical frame articulation structure 750(sometimes referred to herein as a push/pull helical structure)incorporates the components of FIGS. 24A-24G, and provides thefunctionality of the annular extension/contraction frame embodiments ofFIGS. 18-22I. Push/pull structure includes a skeleton defined by innerand outer helical frames 732, 734, and also includes three balloon/coreassemblies 730 a, 730 b, and 730 c, respectively. Each balloon/coreassembly includes a set of balloons at three lateral orientations, 720i, 720 ii, and 720 iii. Balloon/core assembly 730 b extends along ahelical space that is axially between a flange of the inner frame and aflange of the outer frame, and that is radially between a wall of theinner frame and a wall of the outer frame, so that the frames overlapalong this balloon/core assembly. Hence, when balloons 720 ofballoon/core assembly 730 inflate, they push the adjacent flanges apartand increase the overlap of the frames, inducing axial contraction ofthe skeleton, such that the balloons of this assembly function ascontraction balloons. In contrast, balloon/core assemblies 730 a and 730c are radially adjacent to only inner frame 732 (in the case of assembly730 a) or outer frame 734 (in the case of assembly 730 b). Expansion ofthe balloons 720 of assemblies 730 a, 730 c pushes axially againstframes so as to decrease the overlap of the frames, and acts inopposition to the inflation of balloons 720 of assembly 730 b. Hence,balloons 720 of assemblies 730 a, 730 c function as extension balloons.

Referring now to FIGS. 25A-25C, when all the contraction balloons 720 ofassembly 730 b are inflated and all the extension balloons of assemblies730 a, 730 c are deflated, the push/pull structure 750 is in a straightshort configuration as shown in FIG. 25A. Even partial inflation of theextension balloons and even partial deflation of the contractionballoons articulates push/pull structure 750 to a straight intermediatelength configuration, and full inflation of all extension balloons ofassemblies 730 a, 730 c (along with deflation of the contractionballoons) fully axially elongates the structure. As with the ringpush/pull frames, inflating contraction balloons 720 ii along onelateral orientation of assembly 730 b (with corresponding deflation ofthe extension balloons 720 ii of assemblies 730 a, 730 b) locallydecreases the axial length of the skeleton along that side, whileselective deflation of contraction balloons 720 i of assembly 730 b(with corresponding inflation of extension balloons 720 i of assemblies730 a and 730 c) locally increases the length of the skeleton, resultingin the fully laterally bent configuration of FIG. 25E. Note thatextension and contraction balloons along the 720 iii orientation may beinflated and deflated with the extension and contraction orientationballoons of orientation 720 ii so as to keep the curvature in the planeof the drawing as shown. Stiffness of the structure may be modulateduniformly or locally (with axial and/or orientation variations) asdescribed above regarding the ring frame embodiments. Similarly, thenumber of extension and contraction balloons along each orientation(which will often be associated with the number of loops of assemblies730 a, 730 b, etc) may be determined to provide the desired range ofmotion, resolution, and response. As described with reference to thepush/pull ring frame embodiments, the overall articulated portion of thestructure will often be separated into a plurality of independentlycontrollable segments.

Referring now to FIG. 25F, push/pull structure 750 will often include anouter flexible sheath 752 and an inner flexible sheath 754. Sheaths 752,754 may be sealed together at a distal seal 756 distal of the inflationlumens and balloons of assemblies 730, and one or more proximal seal(not shown) may be provided proximal of the balloons and/or near aproximal end of the catheter structure, so as to provide a sealed volumesurrounding the articulation balloons. A vacuum can be applied to thissealed volume, and can be monitored to verify that no leaks are presentin the balloons or inflation lumen system within a patient body.

Referring now to FIGS. 26A and 26B, an alternative push/pull structureomits one of the two extension balloon assemblies 730 a, 730 c, and usesa 1-to-1 extension/contraction balloon opposition arrangement asdescribed above with reference to FIGS. 23A and 23B. Note that thisembodiment retains balloon assembly 730 c that is radially adjacent toouter frame 734 (so that no balloons are visible even with the sheathremoved). Alternative embodiments may retain assembly 730 a and foregoassembly 730 c (so that balloons could be seen through a clear sheath,for example).

Referring now to FIG. 27, short segments of alternative core structuresare shown for comparison. Core shaft 702 has an outer diameter of about0.028″ and 7 lumens, with 6 peripheral lumens having an inner diameterof about 0.004″ readily available for formation associated ports and usein transmitting inflation fluid to and from balloons. A central lumenmight be used, for example, in monitoring of the vacuum system to verifyintegrity of the system. Core shaft 702 can be used, for example, in a14-15 Fr catheter system having two segments that are each capable ofproviding up to 120 degrees of bending (or alternatively more or lessdepending on the number of balloons ganged together on each channel),with such a system optionally capable of providing a bend radiussufficient for to fit a 180 degree bend of the catheter within a spaceof 3 inches or less, ideally within 2½ inches or less, and in some caseswithin 2 inches or less. Such a system may be beneficial for structuralheart therapies, for example, and particularly for mitral valvedelivery, positioning, and/or implantation.

Referring still to FIG. 27, other therapies may benefit from smallercatheter profiles, and do not need the bending forces available from a15 Fr catheter. Electrophysilogy therapies such as AFib ablation fromwithin an atrium of the heart may be good examples of therapies whichwould benefit from the degrees of freedom that can be provided in smallstructures using the systems described herein. Scaling the 15 Fr systemdown for a 7-8 Fr ablation catheter might make use of a directly scaledcore 762 having half the overall outer diameter and half the lumen innerdiameter of core 702, as the pressure-containing stresses in thematerial would scale with the lumen diameters. However, there may becost benefits to maintaining minimum lumen wall thicknesses that areabove 0.002″, preferably at or above 0.0025″, and ideally at or aboveabout 0.003″. Toward that end, and to provide 6 contraction or extensionlumens for two 3D push/pull segments along a common helical core alongwith a desirably small bend radius, it may be beneficial to use radiallyelongate core 764 having 6 lumens that are all surrounded by at least0.003″ of material. Core 764 has an axial height of half of core 702 anda radial width of that is less than half the balloon diameter of the14-15 Fr system. There may be benefits to having the radial (elongate)dimension of the cross-section being less than the inflated innerdiameter of the balloons mounted thereon, to inhibit trapping ofinflation fluid on one axial side of the balloon (away from theinflation port).

Still further advantages may be provided by applying the smaller lumenand wall thickness dimensions of 7 Fr core 762 to a 15 Fr catheter coresize, as it results in the 12 inflation lumen core 766. The large13^(th) lumen of this embodiment may help enhance flexibility of thesegments, and can again be used to monitor system integrity using avacuum system. The 12 lumens may allow, for example, a continuouspush/pull structure to have 4 independently controllable 3D shape (4Dshape+stiffness) segments. A 16 inflation lumen core 768 combines thesmaller lumen and wall thickness with a radially elongate cross-section,allowing 5 independently controllable 3D segments. It should beunderstood that still further numbers of lumens at smaller profiles arepossible using known and relatively low cost multilumen extrusiontechniques.

Referring now to FIGS. 28-38, a number of modifications are shown to theinner and outer helical frame structures described above, along withsome associated components that may help maintain component alignmentwithin the catheter assemblies. As shown in FIGS. 28 and 29, radial cuts1970 or slots may be made in the web of an inner helical frame 1972,with the cuts optionally extending axially and being formed at threelocations separated by about 120 degrees about the frame axis, so thatthe cuts can be positioned between balloons of the assembly. The cutsmay extend through the web between flanges, and optionally along anadjacent inner radial portion of the flanges. Sliding adjacent theopposed cut surfaces may facilitate local axial translation ofarc-segments of the inner frame between cuts in response to balloonactuation, and thereby enhance axial bending and/or elongation of theoverall catheter frame.

Referring now to FIGS. 30-36, alternative inner and outer helical framestructures 1974, 1978, respectively, both have open regions 1976 thatcan be formed, for example, by cutting and removing material from thewebs and adjacent flanges of each loop in 3 places, spaced about 120degrees apart, with the openings ideally being axially aligned withopenings on adjacent loops. The openings may have a circumferentialwidth in a range from about 0.005″ to about 0.030″, and may extendradially along the adjacent flanges for a distance in a range from about0.010″ to about 0.030.″ Flexing of the flanges adjacent the openings mayfacilitate local axial translation of the helical frame segments betweenopenings, and hence axial bending and/or elongation of the overallframe. The radial openings in the frames may also be used to helppromote axial alignment of balloon subsets. More generally, it may beadvantageous to have structures or features disposed along the helicalframes described herein to help promote axial alignment of subsets ofballoons, such as sets 1980 a, 1980 b, 1980 c. Discrete features may beaffixed to some or all of the loops (such as by additive manufacturingor 3-D printing onto the extruded frame structures) with the featureshaving surfaces that are disposed between and will engage against theends of some or all of the balloons. Alternatively, an inner and/orouter sheath 1984, 1986 may have a radially protruding surface that canextend radially through the openings 1976 in the inner frame 1974, outerframe 1978, or both. The extending of openings 1976 along the web and aradial portion of the flange may allow the protruding surfaces of thesheath(s) to extend continuously between frame arc segments, keeping theframe segments in axial alignment. Similarly, the protruding surfacesmay engage any balloon ends if they begin to move out of alignment withtheir subset. Note that one or more protruding feature in one of thesheaths may be sufficient, and that the balloons may be angled on theballoon assemblies (e.g., see angled balloons 1988 on the balloonassembly of FIG. 35) so as to promote axial movement of the framesegments and/or provide circumferentially oriented ends that more evenlyengage the protruding radial alignment surfaces of the sheath(s), as canbe understood with reference to the somewhat axially angled balloon ends1982 of FIG. 36. Optionally, the pitch angles of the flanges may varycircumferentially, for example, with the flanges along the cut sectionshaving a greater pitch angle (measured from a lateral plane) than theflanges between cuts. The balloons being disposed at an angle along themulti-lumen shaft may help limit circumferential loads to the frameswhile enhancing axial loads against the flanges.

Referring now to FIGS. 37 and 38, a still further alternative helicalinner frame structure 1990 may have edge channels or cuts 1992. By, forexample, cutting and removing material from the flanges and adjacentwebs in 3 places on each loop (120 degrees apart), flexibility of theframe may be greatly enhanced. The removed material may have acircumferential width at the flange/web junction of 0.005-0.030″, andmay extend radialy along the full radial length of the flanges. Flexingof the web by balloons disposed between removed flange regions mayfacilitate local axial translation of frame segments between flanges andaxial bending of overall frame. Shape of material removed from web maybe “V” (with straight cuts, as shown), “C” (with curved cuts, optionallybeing drilled), “U” (with straight and curved cuts), or the like.

Referring now to FIGS. 39A-39D, alternative ring frame structures 1402,1404 include axial openings in the flanges of the inner and outer framerings (in FIG. 39B), and optional slots traversing the web of the inneror outer frame between openings (see FIG. 39C). A helical balloon coilhas a series of balloons formed using a continuous balloon tube sealedover a multi-lumen shaft as described above, with the assembly herehaving helical coils formed from perpendicular (or near perpendicular)loops connected together by axially angled sections between loops. Theballoons along each loop may be mounted so that the group is at an anglerelative to the multi-lumen shaft so that the balloons may remaincircumferentially aligned between a pair of flanges while the shaftangles slightly axially. Regardless, the balloon assembly can be wrappedaround the frames and the frames assembled together using the axialapertures. Hence, the helical balloon assemblies described herein can beassembled with the ring frame structures as well as the helical frames.Optionally, an inner or outer sheath 1406 may have a radial protrusionthat can extend into the slot in the ring frames to maintain axialalignment of the ring frames and balloons. A channel in the radialprotrusion may also accommodate a multi-lumen shaft that can be used toarticulate a more distal segment, as shown in FIG. 39D.

It should be understood that still further alternative embodiments maytake advantage of the beneficial components and assemblies describedherein. For example, as can be understood from the disclosure aboveregarding many of the flexible structures of FIGS. 3-12, inflation of aballoon may be resiliently opposed by a helical spring or other biasingstructure so that the spring deflates the balloon and urges a flexiblebody back toward a pre-balloon-inflation state when the inflation fluidis released from the balloon. Rather than relying on 6 dedicated opposedexpansion and contraction balloon channels for each segment (providingindependent contraction and expansion along each lateral orientation) inthe push/pull ring frame and push/pull helical frame embodimentsdescribed above, two or more of the channels (from the same segments orfrom different segments) may be grouped together to act as a commonbaising structure or fluid spring. As an example, all the contractionballoons along two adjacent segments might open to a single lumen thatis inflated to less than full pressure. Modulating pressure to thedifferent sets of extension balloons may still allow the extensionballoons to articulate each segment with three independent degrees offreedom, as the grouped contraction balloons could selectively beoverpowered by the extension balloons (like the coil springs) or may beallowed to deflate the extension balloons. In some embodiments, ratherthan relying on partial pressure of extension or contraction balloons,an elastomeric material may be mounted over the core of some or all ofthe extension or contraction balloons of a segment so as to passivelyoppose a set of the balloons.

While the exemplary embodiment have been described in some detail forclarity of understanding and by way of example, a variety ofmodifications, changes, and adaptations of the structures and methodsdescribed herein will be obvious to those of skill in the art. Hence,the scope of the present invention is limited solely by the claimsattached hereto.

What is claimed is:
 1. An articulable catheter comprising: at least oneelongate skeleton having a proximal end and a distal end and defining anaxis therebetween, the skeleton including an inner wall and an outerwall with a first flange affixed to the inner wall and a second flangeaffixed to the outer wall, opposed major surfaces of the walls beingoriented primarily radially and opposed major surfaces of the flangesbeing oriented primarily axially; and a plurality of axial contractionballoons disposed radially between the inner wall and the outer wall andaxially between the first flange and the second flange so that, in use,inflation of the contraction balloons pushes the first and secondflanges axially apart so as to urge an axial overlap of the inner andouter walls to increase such that the skeleton adjacent the inflatedcontraction balloons is locally urged to axially contract.
 2. Thearticulable catheter of claim 1, wherein the skeleton comprises aplurality of annular structures including a plurality of inner ringshaving the inner walls and a plurality of outer rings having the outerwalls, wherein the flanges comprise annular flanges affixed to thewalls, the annular structures being axially movable relative to eachother.
 3. The articulable catheter of claim 2, wherein each ring has anassociated one of the walls and has a proximal ring end and a distalring end with the wall of the ring affixed to an associated proximalflange at the proximal ring end and to an associated distal flange atthe distal ring end, the first and second flanges being included amongthe proximal and distal flanges.
 4. The articulable catheter of claim 1,wherein the skeleton comprises at least one helical member, wherein thewalls comprise helical walls, and wherein the flanges comprise helicalflanges affixed to the helical walls, the helical member(s) includingthe walls and flanges and defining a plurality of helical loops, theloops being axially movable relative to each other.
 5. The articulablecatheter of claim 4, wherein each loop has an associated wall with aproximal loop edge and a distal loop edge, the wall being affixed to anassociated proximal flange at the proximal loop edge and to anassociated distal flange at the distal loop edge, the first and secondflanges being included among the proximal and distal flanges.
 6. Thearticulable catheter of claim 4, wherein the helical member has openingsextending radially through the walls or axially through the flanges orboth, the openings being disposed circumferentially betweencircumferentially adjacent balloons and enhancing axial flexibility ofthe skeleton.
 7. The articulable catheter of claim 1, further comprisinga plurality of axial extension balloons disposed axially betweenadjacent flanges of the skeleton, only one of the walls of the skeletonbeing disposed radially of the extension balloons so that, in use,expansion of the extension balloons pushes the adjacent flanges axiallyapart so as to urge the skeleton adjacent the inflated extensionballoons to locally elongate axially.
 8. The articulable catheter ofclaim 7, wherein the extension balloons and the contraction balloons aremounted in opposition so that inflation of the extension balloons anddeflation of the contraction balloons locally axially elongates theskeleton and so that deflation of the extension balloons and inflationof the contraction balloons locally axially contracts the skeleton. 9.The articulable catheter of claim 7, wherein the balloons aredistributed circumferentially about the axis so that selective inflationof a first eccentric subset of the balloons and selective deflation of asecond eccentric subset of the balloons laterally deflects the axistoward a first lateral orientation, and selective deflation of the firsteccentric subset of the balloons and selective inflation of the secondeccentric subset of the balloons laterally deflects the axis away fromthe first lateral orientation.
 10. The articulable catheter of claim 7,wherein the balloons are distributed axially along the axis so thatselective inflation of a third eccentric subset of the balloons andselective deflation of a fourth eccentric subset of the balloonslaterally deflects the axis along a first axial segment of the skeleton,and selective deflation of a fifth eccentric subset of the balloons andselective inflation of a sixth eccentric subset of the balloonslaterally deflects the axis along a second axial segment of theskeleton, the second axial segment being axially offset from the firstaxial segment.
 11. The articulable catheter of claim 1, wherein a firstplurality of the balloons has outer surfaces defined by a sharedflexible tube, wherein a multi-lumen shaft is disposed within theflexible tube with radial ports extending between interiors of theballoons and a plurality of lumens of the multi-lumen shaft so as tofacilitate inflation of selectable subsets of the balloons by directingfluid along a subset of the lumens.
 12. An articulable device or systemaccording to claim 1, wherein an array of the balloons is mounted on anextruded multi-lumen helical core, and wherein each balloon has anassociated port from an outer surface of the helical core to anassociated lumen of the core, a plurality of the balloons being alignedalong a common lateral orientation and being in fluid communication witha first lumen of the multi-lumen core via the associated ports.
 13. Anarticulable flexible device comprising: an elongate structural skeletonhaving a proximal end and a distal end with an axis therebetween, thestructural skeleton having a helical member and an axial segment betweenthe proximal and distal ends; a helical fluid conduit extending axiallyalong the skeleton, the conduit having a plurality of fluid channels;and a plurality of fluid-expandable bodies distributed axially andcircumferentially along the segment and coupled to the fluid channels sothat inflation of the balloons during use bends the skeleton along thesegment in first and second transverse lateral bending axes, and alsoaxially elongates the skeleton along the segment so that the segment ofthe skeleton articulates with three degrees of freedom.
 14. Thearticulable flexible device of claim 13, wherein: a first subset of thefluid-expandable bodies is disposed substantially axisymmetrical alongthe segment of the skeleton such that inflation of the first subsetaxially elongates the segment; a second subset of the fluid-expandablebodies is distributed eccentrically along the segment such thatinflation of the second subset laterally bends the segment along thefirst lateral bending axis; a third subset of the fluid-expandablebodies is distributed substantially eccentrically along the segment suchthat inflation of the third subset laterally bends the segment along thesecond lateral bending axis and transverse to the first bending axis,the second and third subsets axially overlapping the first subset; and afourth subset of the fluid-expandable bodies is substantially inopposition to the first subset and a fifth subset of thefluid-expandable bodies is substantially in opposition to the secondsubset and a sixth subset of the fluid expandable bodies issubstantially in opposition to the third subset so that selectiveinflation of the subsets controllably articulates the segment throughouta three-dimensional workspace.
 15. A method for articulating an elongateflexible device, the method comprising: directing fluid distally alongan elongate flexible body of the device, the device having a pluralityof fluid expandable bodies distributed along and about an axis extendingalong the body, wherein the fluid is directed toward a subset of thefluid expandable bodies so as to expand the expandable bodies of thesubset; and locally axially contracting the elongate body adjacent theexpandable bodies of the subset in response to expanding of theexpandable bodies of the subset so as to urge the device to bendlaterally toward the subset, decrease in axial length, increase inlateral bending stiffness, or a combination thereof.
 16. An articulablesystem comprising: an elongate flexible structural skeleton having aproximal end and a distal end with an axis extending therebetween, theskeleton comprising a plurality of members extending primarilycircumferentially about the axis, the members having flanges extendingprimarily radially from walls extending primarily axially, adjacentflanges of adjacent members separated by local offsets that vary withlateral bending of the skeleton or axial elongation of the skeleton orboth; and a plurality of fluid expandable bodies disposed in the offsetsof the skeleton and configured to couple with a fluid supply system soas to selectably expand a subset of the fluid expandable bodies andalter a bend state of the axis, an elongation state of the axis, alateral bending stiffness of the axis, or a combination thereof.